#include "sema.h"
#include <stdio.h>
#include <string.h>

// === 类型关系 ===
static TypeKind current_return_type = TYPE_VOID;
static const char* current_return_struct_name = NULL;

static TypeKind promote(TypeKind a, TypeKind b) {
    // 枚举在算术运算中视为 i64
    if (a == TYPE_ENUM) a = TYPE_I64;
    if (b == TYPE_ENUM) b = TYPE_I64;
    if (a == TYPE_F64 || b == TYPE_F64) return TYPE_F64;
    if (a == TYPE_I64 || b == TYPE_I64) return TYPE_I64;
    if (a == TYPE_BOOL || b == TYPE_BOOL) return TYPE_BOOL;
    return TYPE_ERROR;
}

static bool is_numeric(TypeKind t) { return t == TYPE_I64 || t == TYPE_F64 || t == TYPE_ENUM; }
static bool is_comparable(TypeKind a, TypeKind b) {
    if (a == b) return true;
    // 枚举可以参与整数比较
    if ((a == TYPE_I64 && b == TYPE_ENUM) || (a == TYPE_ENUM && b == TYPE_I64)) return true;
    return false;
}

// === 向前声明 ===
static void analyze_node(AstNode* node, Scope* scope, ErrorList* errors, Arena* a);

// === 检查表达式 ===
static void analyze_expr(AstNode* node, Scope* scope, ErrorList* errors, Arena* a) {
    switch (node->kind) {
    case AST_LITERAL_EXPR:
        break;  // 类型已在创建时设置

    case AST_IDENT_EXPR: {
        Symbol* sym = scope_lookup(scope, node->as.ident.name);
        if (!sym) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "未定义的变量 '%s'", node->as.ident.name);
            node->type.kind = TYPE_ERROR;
        } else if (sym->is_type_alias) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "'%s' 是类型别名，不能作为表达式使用", node->as.ident.name);
            node->type.kind = TYPE_ERROR;
        } else if (sym->kind == SYM_FUNCTION) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "'%s' 是函数，不能作为表达式使用", node->as.ident.name);
            node->type.kind = TYPE_ERROR;
        } else {
            node->type.kind = sym->type;
            if (sym->type == TYPE_STRUCT && sym->struct_type_name) {
                node->type.struct_name = sym->struct_type_name;
            }
            if (sym->type == TYPE_ARRAY) {
                node->type.element_type = sym->array_element_type;
                node->type.element_struct_name = sym->array_element_struct_name;
                node->type.array_size = sym->array_size;
            }
        }
        break;
    }

    case AST_UNARY_EXPR: {
        analyze_expr(node->as.unary.operand, scope, errors, a);
        TypeKind inner = node->as.unary.operand->type.kind;
        if (node->as.unary.op == OP_NEG) {
            if (!is_numeric(inner)) {
                error_add(errors, "<sema>", node->loc.line, node->loc.col,
                          "一元 '-' 只能用于数值类型");
                node->type.kind = TYPE_ERROR;
            } else {
                node->type.kind = inner;
            }
        } else {  // OP_NOT
            if (inner != TYPE_BOOL) {
                error_add(errors, "<sema>", node->loc.line, node->loc.col,
                          "'!' 只能用于布尔类型，得到 '%s'", type_name(inner));
                node->type.kind = TYPE_ERROR;
            } else {
                node->type.kind = TYPE_BOOL;
            }
        }
        break;
    }

    case AST_BINARY_EXPR: {
        analyze_expr(node->as.binary.left, scope, errors, a);
        analyze_expr(node->as.binary.right, scope, errors, a);
        TypeKind l = node->as.binary.left->type.kind;
        TypeKind r = node->as.binary.right->type.kind;
        if (l == TYPE_ERROR || r == TYPE_ERROR) { node->type.kind = TYPE_ERROR; break; }

        switch (node->as.binary.op) {
        case OP_ADD:
            if (l == TYPE_STR || r == TYPE_STR) {
                // 字符串拼接：两边都必须是 str 类型
                if (l != TYPE_STR || r != TYPE_STR) {
                    error_add(errors, "<sema>", node->loc.line, node->loc.col,
                              "字符串拼接需要两边都是 str 类型，得到 '%s' + '%s'",
                              type_name(l), type_name(r));
                    node->type.kind = TYPE_ERROR;
                } else {
                    node->type.kind = TYPE_STR;
                }
            } else if (!is_numeric(l) || !is_numeric(r)) {
                error_add(errors, "<sema>", node->loc.line, node->loc.col,
                          "算术运算需要数值类型");
                node->type.kind = TYPE_ERROR;
            } else {
                node->type.kind = promote(l, r);
            }
            break;
        case OP_SUB: case OP_MUL: case OP_DIV: case OP_MOD:
            if (!is_numeric(l) || !is_numeric(r)) {
                error_add(errors, "<sema>", node->loc.line, node->loc.col,
                          "算术运算需要数值类型");
                node->type.kind = TYPE_ERROR;
            } else {
                node->type.kind = promote(l, r);
            }
            break;
        case OP_EQ: case OP_NE: case OP_LT: case OP_GT: case OP_LE: case OP_GE:
            if (!is_comparable(l, r)) {
                error_add(errors, "<sema>", node->loc.line, node->loc.col,
                          "类型 '%s' 和 '%s' 无法比较", type_name(l), type_name(r));
                node->type.kind = TYPE_ERROR;
            } else {
                node->type.kind = TYPE_BOOL;
            }
            break;
        case OP_AND: case OP_OR:
            if (l != TYPE_BOOL || r != TYPE_BOOL) {
                error_add(errors, "<sema>", node->loc.line, node->loc.col,
                          "逻辑运算需要布尔类型");
                node->type.kind = TYPE_ERROR;
            } else {
                node->type.kind = TYPE_BOOL;
            }
            break;
        default: break;
        }
        break;
    }

    case AST_CALL_EXPR: {
        Symbol* sym = scope_lookup(scope, node->as.call.name);
        if (!sym || sym->kind != SYM_FUNCTION) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "未定义的函数 '%s'", node->as.call.name);
            node->type.kind = TYPE_ERROR;
            // 即使函数未定义，也要分析参数表达式（它们可能有更多错误）
            for (size_t i = 0; i < node->as.call.arg_count; i++) {
                analyze_expr(node->as.call.args[i], scope, errors, a);
            }
            break;
        }
        if (node->as.call.arg_count != sym->param_count) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "函数 '%s' 需要 %zu 个参数，但提供了 %zu 个",
                      node->as.call.name, sym->param_count, node->as.call.arg_count);
            node->type.kind = TYPE_ERROR;
            // 即使参数数量不匹配，也分析已有的参数
            for (size_t i = 0; i < node->as.call.arg_count; i++) {
                analyze_expr(node->as.call.args[i], scope, errors, a);
            }
            break;
        }
        for (size_t i = 0; i < node->as.call.arg_count; i++) {
            analyze_expr(node->as.call.args[i], scope, errors, a);
            TypeKind actual = node->as.call.args[i]->type.kind;
            TypeKind expected = sym->param_types[i];
            if (actual != TYPE_ERROR) {
                if (expected == TYPE_STRUCT) {
                    // 结构体参数：比较具体类型名
                    const char* actual_name = node->as.call.args[i]->type.struct_name;
                    const char* expected_name = sym->param_struct_names ? sym->param_struct_names[i] : NULL;
                    if (actual != TYPE_STRUCT || !actual_name || !expected_name ||
                        strcmp(actual_name, expected_name) != 0) {
                        error_add(errors, "<sema>", node->loc.line, node->loc.col,
                                  "参数 %zu 类型不匹配: 期望 '%s'，得到 '%s'",
                                  i + 1,
                                  expected_name ? expected_name : "struct",
                                  actual_name ? actual_name : type_name(actual));
                    }
                } else if (actual != expected &&
                           !(expected == TYPE_I64 && actual == TYPE_ENUM)) {
                    error_add(errors, "<sema>", node->loc.line, node->loc.col,
                              "参数 %zu 类型不匹配: 期望 '%s'，得到 '%s'",
                              i + 1, type_name(expected), type_name(actual));
                }
            }
        }
        node->type.kind = sym->return_type;
        if (sym->return_type == TYPE_STRUCT && sym->return_struct_type_name) {
            node->type.struct_name = sym->return_struct_type_name;
        }
        break;
    }

    case AST_FIELD_ACCESS: {
        analyze_expr(node->as.field_access.object, scope, errors, a);
        AstNode* obj = node->as.field_access.object;
        if (obj->type.kind == TYPE_ERROR) {
            node->type.kind = TYPE_ERROR;
            break;
        }
        if (obj->type.kind != TYPE_STRUCT) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "类型 '%s' 不是结构体，不能访问字段 '%s'",
                      type_name(obj->type.kind), node->as.field_access.field);
            node->type.kind = TYPE_ERROR;
            break;
        }
        // 查找结构体定义
        const char* struct_name = obj->type.struct_name;
        if (!struct_name) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "无法确定结构体类型");
            node->type.kind = TYPE_ERROR;
            break;
        }
        Symbol* struct_sym = scope_lookup_struct(scope, struct_name);
        if (!struct_sym) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "未定义的结构体 '%s'", struct_name);
            node->type.kind = TYPE_ERROR;
            break;
        }
        int fi = scope_struct_field_index(struct_sym, node->as.field_access.field);
        if (fi < 0) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "结构体 '%s' 没有字段 '%s'", struct_name, node->as.field_access.field);
            node->type.kind = TYPE_ERROR;
            break;
        }
        node->type.kind = struct_sym->struct_field_types[fi];
        node->as.field_access.field_index = fi;
        // 如果字段也是结构体类型，传播类型名
        if (node->type.kind == TYPE_STRUCT &&
            struct_sym->struct_field_struct_names &&
            struct_sym->struct_field_struct_names[fi]) {
            node->type.struct_name = struct_sym->struct_field_struct_names[fi];
        }
        break;
    }

    case AST_STRUCT_INIT: {
        const char* resolved_type_name = node->as.struct_init.type_name;
        Symbol* struct_sym = scope_lookup_struct(scope, resolved_type_name);
        if (!struct_sym) {
            // 检查是否是类型别名指向结构体
            Symbol* alias_sym = scope_lookup(scope, resolved_type_name);
            if (alias_sym && alias_sym->is_type_alias && alias_sym->struct_type_name) {
                resolved_type_name = alias_sym->struct_type_name;
                struct_sym = scope_lookup_struct(scope, resolved_type_name);
                // 更新 type_name 为真实结构体名（codegen 需要）
                node->as.struct_init.type_name = resolved_type_name;
            }
        }
        if (!struct_sym) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "未定义的结构体类型 '%s'", node->as.struct_init.type_name);
            node->type.kind = TYPE_ERROR;
            break;
        }
        if (node->as.struct_init.field_count != struct_sym->struct_field_count) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "结构体 '%s' 有 %zu 个字段，但提供了 %zu 个",
                      node->as.struct_init.type_name,
                      struct_sym->struct_field_count,
                      node->as.struct_init.field_count);
            node->type.kind = TYPE_ERROR;
            break;
        }
        // 检查每个字段名和类型匹配
        for (size_t i = 0; i < node->as.struct_init.field_count; i++) {
            const char* fname = node->as.struct_init.field_names[i];
            AstNode* fval = node->as.struct_init.field_values[i];
            analyze_expr(fval, scope, errors, a);

            int fi = scope_struct_field_index(struct_sym, fname);
            if (fi < 0) {
                error_add(errors, "<sema>", node->loc.line, node->loc.col,
                          "结构体 '%s' 没有字段 '%s'",
                          node->as.struct_init.type_name, fname);
                node->type.kind = TYPE_ERROR;
                continue;
            }
            TypeKind expected = struct_sym->struct_field_types[fi];
            TypeKind actual = fval->type.kind;
            if (actual != TYPE_ERROR && actual != expected) {
                error_add(errors, "<sema>", node->loc.line, node->loc.col,
                          "字段 '%s' 类型不匹配: 期望 '%s'，得到 '%s'",
                          fname, type_name(expected), type_name(actual));
            }
        }
        if (node->type.kind != TYPE_ERROR) {
            node->type.kind = TYPE_STRUCT;
            node->type.struct_name = resolved_type_name;
        }
        break;
    }

    case AST_ENUM_VARIANT: {
        Symbol* enum_sym = scope_lookup_struct(scope, node->as.enum_variant.enum_name);
        if (!enum_sym || enum_sym->kind != SYM_ENUM) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "未定义的枚举 '%s'", node->as.enum_variant.enum_name);
            node->type.kind = TYPE_ERROR; break;
        }
        int vi = scope_enum_variant_index(enum_sym, node->as.enum_variant.variant_name);
        if (vi < 0) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "枚举 '%s' 没有变体 '%s'",
                      node->as.enum_variant.enum_name,
                      node->as.enum_variant.variant_name);
            node->type.kind = TYPE_ERROR; break;
        }
        node->as.enum_variant.variant_index = vi;
        node->type.kind = TYPE_ENUM;
        break;
    }

    case AST_INDEX_EXPR: {
        analyze_expr(node->as.index_expr.array, scope, errors, a);
        analyze_expr(node->as.index_expr.index, scope, errors, a);
        AstNode* arr = node->as.index_expr.array;
        AstNode* idx = node->as.index_expr.index;

        if (arr->type.kind == TYPE_ERROR) { node->type.kind = TYPE_ERROR; break; }
        if (arr->type.kind != TYPE_ARRAY) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "类型 '%s' 不支持索引操作", type_name(arr->type.kind));
            node->type.kind = TYPE_ERROR; break;
        }
        if (idx->type.kind == TYPE_ERROR) { node->type.kind = TYPE_ERROR; break; }
        if (idx->type.kind != TYPE_I64) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "数组索引必须是 i64 类型, 得到 '%s'", type_name(idx->type.kind));
            node->type.kind = TYPE_ERROR; break;
        }
        // 结果类型 = 元素类型
        node->type.kind = arr->type.element_type;
        node->type.struct_name = arr->type.element_struct_name;
        break;
    }

    case AST_METHOD_CALL: {
        analyze_expr(node->as.method_call.receiver, scope, errors, a);
        const char* recv_struct = node->as.method_call.receiver->type.struct_name;
        if (node->as.method_call.receiver->type.kind != TYPE_STRUCT || !recv_struct) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "只有结构体类型支持方法调用");
            node->type.kind = TYPE_ERROR; break;
        }
        // 构造改名后的函数名并查找
        char mangled[256];
        snprintf(mangled, sizeof(mangled), "%s$%s", recv_struct,
                 node->as.method_call.method_name);
        Symbol* sym = scope_lookup(scope, mangled);
        if (!sym || sym->kind != SYM_FUNCTION) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "结构体 '%s' 没有方法 '%s'", recv_struct,
                      node->as.method_call.method_name);
            node->type.kind = TYPE_ERROR; break;
        }
        // 检查参数数量（用户提供的参数 + 隐含的 self）
        if (node->as.method_call.arg_count + 1 != sym->param_count) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "方法 '%s' 需要 %zu 个参数，提供了 %zu 个",
                      node->as.method_call.method_name,
                      sym->param_count > 0 ? sym->param_count - 1 : 0,
                      node->as.method_call.arg_count);
            node->type.kind = TYPE_ERROR; break;
        }
        // 对每个参数进行类型检查（跳过 self 参数，即 sym->param_types[0] 是 self 的类型）
        for (size_t i = 0; i < node->as.method_call.arg_count; i++) {
            analyze_expr(node->as.method_call.args[i], scope, errors, a);
            TypeKind actual = node->as.method_call.args[i]->type.kind;
            TypeKind expected = sym->param_types[i + 1];
            if (actual != TYPE_ERROR && actual != expected &&
                !(expected == TYPE_I64 && actual == TYPE_ENUM)) {
                if (expected == TYPE_STRUCT) {
                    // 结构体类型参数：比较具体类型名
                    const char* actual_name = node->as.method_call.args[i]->type.struct_name;
                    const char* expected_name = sym->param_struct_names ? sym->param_struct_names[i + 1] : NULL;
                    if (!actual_name || !expected_name || strcmp(actual_name, expected_name) != 0) {
                        error_add(errors, "<sema>", node->loc.line, node->loc.col,
                                  "参数 %zu 类型不匹配: 期望 '%s'，得到 '%s'",
                                  i + 1,
                                  expected_name ? expected_name : "struct",
                                  actual_name ? actual_name : type_name(actual));
                    }
                } else {
                    error_add(errors, "<sema>", node->loc.line, node->loc.col,
                              "参数 %zu 类型不匹配: 期望 '%s'，得到 '%s'",
                              i + 1, type_name(expected), type_name(actual));
                }
            }
        }
        node->type.kind = sym->return_type;
        if (sym->return_type == TYPE_STRUCT && sym->return_struct_type_name) {
            node->type.struct_name = sym->return_struct_type_name;
        }
        break;
    }

    default: break;
    }
}

static void analyze_node(AstNode* node, Scope* scope, ErrorList* errors, Arena* a) {
    if (!node) return;

    switch (node->kind) {
    case AST_PROGRAM:
        // Pass 0: 注册类型别名
        for (size_t i = 0; i < node->as.program.alias_count; i++) {
            AstNode* alias = node->as.program.type_aliases[i];
            Symbol* sym = scope_insert(scope, a, alias->as.type_alias.name,
                                        SYM_VARIABLE, alias->as.type_alias.aliased_type);
            if (sym) {
                sym->is_type_alias = true;
                if (alias->as.type_alias.aliased_struct_name) {
                    sym->struct_type_name = alias->as.type_alias.aliased_struct_name;
                }
            }
        }
        // 注册枚举
        for (size_t i = 0; i < node->as.program.enum_count; i++) {
            AstNode* ed = node->as.program.enums[i];
            scope_insert_enum(scope, a, ed->as.enum_decl.name,
                              ed->as.enum_decl.variants,
                              ed->as.enum_decl.variant_count);
        }
        // 第一遍：收集所有结构体定义
        for (size_t i = 0; i < node->as.program.struct_count; i++) {
            AstNode* sd = node->as.program.structs[i];
            const char** fnames = (const char**)arena_alloc_impl(a,
                sd->as.struct_decl.field_count * sizeof(const char*));
            TypeKind* ftypes = (TypeKind*)arena_alloc_impl(a,
                sd->as.struct_decl.field_count * sizeof(TypeKind));
            const char** fstruct_names = (const char**)arena_alloc_impl(a,
                sd->as.struct_decl.field_count * sizeof(const char*));
            for (size_t j = 0; j < sd->as.struct_decl.field_count; j++) {
                fnames[j] = sd->as.struct_decl.fields[j]->as.parameter.name;
                ftypes[j] = sd->as.struct_decl.fields[j]->as.parameter.type;
                fstruct_names[j] = sd->as.struct_decl.fields[j]->as.parameter.struct_type_name;
            }
            scope_insert_struct(scope, a, sd->as.struct_decl.name,
                                fnames, ftypes, fstruct_names,
                                sd->as.struct_decl.field_count);
        }
        // 处理 impl 块：将方法名改写为 StructName$methodName，
        // 并自动添加 self 参数（第一个参数），然后注册为普通函数。
        // 同时将改写后的方法追加到程序 functions 数组方便后续 codegen。
        {
            // 先统计需要新增多少个函数（impl 中的方法总数）
            size_t extra_fn = 0;
            for (size_t i = 0; i < node->as.program.impl_count; i++) {
                AstNode* impl = node->as.program.impls[i];
                extra_fn += impl->as.impl_block.method_count;
            }
            if (extra_fn > 0) {
                AstNode** new_fns = (AstNode**)arena_alloc_impl(a,
                    (node->as.program.fn_count + extra_fn) * sizeof(AstNode*));
                memcpy(new_fns, node->as.program.functions,
                       node->as.program.fn_count * sizeof(AstNode*));
                size_t write_pos = node->as.program.fn_count;

                for (size_t i = 0; i < node->as.program.impl_count; i++) {
                    AstNode* impl = node->as.program.impls[i];
                    const char* st_name = impl->as.impl_block.struct_name;
                    // 验证目标结构体存在
                    Symbol* st_sym = scope_lookup_struct(scope, st_name);
                    if (!st_sym) {
                        error_add(errors, "<sema>", impl->loc.line, impl->loc.col,
                                  "impl 的目标结构体 '%s' 未定义", st_name);
                        continue;
                    }
                    for (size_t j = 0; j < impl->as.impl_block.method_count; j++) {
                        AstNode* method = impl->as.impl_block.methods[j];
                        // 构造改名后的函数名
                        char mangled[256];
                        snprintf(mangled, sizeof(mangled), "%s$%s", st_name,
                                 method->as.function.name);
                        method->as.function.name = arena_strdup_impl(a, mangled,
                            strlen(mangled));
                        // 追加到新 functions 数组
                        new_fns[write_pos++] = method;
                    }
                }
                // 更新程序节点
                node->as.program.functions = new_fns;
                node->as.program.fn_count = node->as.program.fn_count + extra_fn;
            }
        }

        // 第二遍：收集所有函数签名
        for (size_t i = 0; i < node->as.program.fn_count; i++) {
            AstNode* fn = node->as.program.functions[i];
            TypeKind* pts = (TypeKind*)arena_alloc_impl(a, fn->as.function.param_count * sizeof(TypeKind));
            const char** pstruct_names = (const char**)arena_alloc_impl(a, fn->as.function.param_count * sizeof(const char*));
            for (size_t j = 0; j < fn->as.function.param_count; j++) {
                TypeKind pt = fn->as.function.params[j]->as.parameter.type;
                const char* psn = fn->as.function.params[j]->as.parameter.struct_type_name;
                // 解析参数类型的别名
                if (psn) {
                    Symbol* as = scope_lookup(scope, psn);
                    if (as && as->is_type_alias) {
                        pt = as->type;
                        psn = as->struct_type_name;
                    }
                }
                pts[j] = pt;
                pstruct_names[j] = psn;
            }
            // 解析返回类型的别名
            TypeKind ret_t = fn->as.function.return_type;
            const char* ret_sn = fn->as.function.return_struct_type_name;
            if (ret_sn) {
                Symbol* as = scope_lookup(scope, ret_sn);
                if (as && as->is_type_alias) {
                    ret_t = as->type;
                    ret_sn = as->struct_type_name;
                }
            }
            scope_insert_function(scope, a, fn->as.function.name,
                                  ret_t, ret_sn,
                                  pts, pstruct_names,
                                  fn->as.function.param_count);
        }
        // 第三遍：分析每个函数体
        for (size_t i = 0; i < node->as.program.fn_count; i++) {
            analyze_node(node->as.program.functions[i], scope, errors, a);
        }
        break;

    case AST_FUNCTION: {
        Scope* fn_scope = scope_new(a, scope);
        // 注册参数（同时解析类型别名，更新 AST 节点供 codegen 使用）
        for (size_t i = 0; i < node->as.function.param_count; i++) {
            AstNode* p = node->as.function.params[i];
            TypeKind pt = p->as.parameter.type;
            const char* psn = p->as.parameter.struct_type_name;
            if (psn) {
                Symbol* as = scope_lookup(scope, psn);
                if (as && as->is_type_alias) {
                    pt = as->type;
                    psn = as->struct_type_name;
                    // 更新 AST 节点
                    p->as.parameter.type = pt;
                    p->as.parameter.struct_type_name = psn;
                }
            }
            Symbol* sym = scope_insert(fn_scope, a, p->as.parameter.name, SYM_PARAMETER, pt);
            if (sym && pt == TYPE_STRUCT && psn) {
                sym->struct_type_name = psn;
            }
        }
        // 解析返回类型的别名
        const char* ret_sn = node->as.function.return_struct_type_name;
        if (ret_sn) {
            Symbol* as = scope_lookup(scope, ret_sn);
            if (as && as->is_type_alias) {
                node->as.function.return_type = as->type;
                node->as.function.return_struct_type_name = as->struct_type_name;
            }
        }
        TypeKind saved = current_return_type;
        const char* saved_name = current_return_struct_name;
        current_return_type = node->as.function.return_type;
        current_return_struct_name = node->as.function.return_struct_type_name;
        analyze_node(node->as.function.body, fn_scope, errors, a);
        current_return_type = saved;
        current_return_struct_name = saved_name;
        break;
    }

    case AST_BLOCK:
        for (size_t i = 0; i < node->as.block.stmt_count; i++) {
            analyze_node(node->as.block.stmts[i], scope, errors, a);
        }
        break;

    case AST_LET_STMT: {
        TypeKind var_type;
        const char* var_struct_name = NULL;
        bool is_array_type = false;

        if (node->as.let_stmt.has_type_annot) {
            if (node->as.let_stmt.annot_type == TYPE_ARRAY) {
                // 数组类型标注: 跳过 init 分析 (init 是自引用的占位符)
                is_array_type = true;
                var_type = TYPE_ARRAY;
            } else {
                analyze_expr(node->as.let_stmt.init, scope, errors, a);
                TypeKind inferred = node->as.let_stmt.init->type.kind;
                const char* annot_struct = node->as.let_stmt.struct_type_name;
                if (annot_struct) {
                    // 先检查是否是类型别名
                    Symbol* alias_sym = scope_lookup(scope, annot_struct);
                    if (alias_sym && alias_sym->is_type_alias) {
                        var_type = alias_sym->type;
                        var_struct_name = alias_sym->struct_type_name;
                    } else {
                        // struct 类型标注
                        Symbol* st_sym = scope_lookup_struct(scope, annot_struct);
                        if (!st_sym) {
                            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                                      "未定义的类型 '%s'", annot_struct);
                            break;
                        }
                        var_type = TYPE_STRUCT;
                        var_struct_name = annot_struct;
                    }
                } else {
                    var_type = node->as.let_stmt.annot_type;
                }
                if (inferred != TYPE_ERROR && inferred != var_type) {
                    error_add(errors, "<sema>", node->loc.line, node->loc.col,
                              "变量 '%s' 类型标注为 '%s'，但初始化表达式类型为 '%s'",
                              node->as.let_stmt.name,
                              annot_struct ? annot_struct : type_name(var_type),
                              type_name(inferred));
                }
            }
        } else {
            analyze_expr(node->as.let_stmt.init, scope, errors, a);
            TypeKind inferred = node->as.let_stmt.init->type.kind;
            // 类型推断
            if (inferred == TYPE_ERROR || inferred == TYPE_VOID) {
                error_add(errors, "<sema>", node->loc.line, node->loc.col,
                          "无法从表达式推断变量 '%s' 的类型", node->as.let_stmt.name);
                break;
            }
            var_type = inferred;
            if (inferred == TYPE_STRUCT) {
                var_struct_name = node->as.let_stmt.init->type.struct_name;
            }
        }

        node->type.kind = var_type;
        node->type.struct_name = var_struct_name;
        if (is_array_type) {
            node->type.element_type = node->as.let_stmt.annot_element_type;
            node->type.element_struct_name = node->as.let_stmt.annot_element_struct_name;
            node->type.array_size = node->as.let_stmt.annot_array_size;
        }
        Symbol* sym = scope_insert(scope, a, node->as.let_stmt.name, SYM_VARIABLE, var_type);
        if (!sym) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "变量 '%s' 重复定义", node->as.let_stmt.name);
        } else {
            sym->is_mut = node->as.let_stmt.is_mut;
            if (var_struct_name) {
                sym->type = TYPE_STRUCT;
                sym->struct_type_name = var_struct_name;
            }
            if (is_array_type) {
                sym->array_element_type = node->type.element_type;
                sym->array_element_struct_name = node->type.element_struct_name;
                sym->array_size = node->type.array_size;
            }
        }
        break;
    }

    case AST_ASSIGN_STMT: {
        Symbol* sym = scope_lookup(scope, node->as.assign_stmt.name);
        if (!sym) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "未定义的变量 '%s'", node->as.assign_stmt.name);
            node->type.kind = TYPE_ERROR;
            break;
        }
        if (sym->kind != SYM_VARIABLE) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "'%s' 不是变量，不能赋值", node->as.assign_stmt.name);
            node->type.kind = TYPE_ERROR;
            break;
        }
        if (!sym->is_mut) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "不能对不可变变量 '%s' 赋值（需用 var 声明）",
                      node->as.assign_stmt.name);
            node->type.kind = TYPE_ERROR;
            break;
        }
        analyze_expr(node->as.assign_stmt.value, scope, errors, a);
        TypeKind value_ty = node->as.assign_stmt.value->type.kind;
        if (value_ty != TYPE_ERROR && value_ty != sym->type) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "赋值类型不匹配: 变量 '%s' 类型为 '%s'，但表达式类型为 '%s'",
                      node->as.assign_stmt.name, type_name(sym->type), type_name(value_ty));
        }
        node->type.kind = TYPE_VOID;
        break;
    }

    case AST_ARRAY_ASSIGN_STMT: {
        Symbol* sym = scope_lookup(scope, node->as.array_assign.name);
        if (!sym) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "未定义的变量 '%s'", node->as.array_assign.name);
            node->type.kind = TYPE_ERROR; break;
        }
        if (sym->type != TYPE_ARRAY) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "'%s' 不是数组类型，不能使用索引赋值", node->as.array_assign.name);
            node->type.kind = TYPE_ERROR; break;
        }
        analyze_expr(node->as.array_assign.index, scope, errors, a);
        analyze_expr(node->as.array_assign.value, scope, errors, a);
        AstNode* idx = node->as.array_assign.index;
        AstNode* val = node->as.array_assign.value;
        if (idx->type.kind != TYPE_ERROR && idx->type.kind != TYPE_I64) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "数组索引必须是 i64 类型, 得到 '%s'", type_name(idx->type.kind));
        }
        TypeKind elem_kind = (sym->type == TYPE_ARRAY) ? sym->array_element_type : sym->type;
        if (val->type.kind != TYPE_ERROR && val->type.kind != elem_kind) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "数组元素类型不匹配: 期望 '%s'，得到 '%s'",
                      type_name(elem_kind), type_name(val->type.kind));
        }
        // struct 元素类型时还需检查结构体名是否匹配
        if (val->type.kind != TYPE_ERROR && elem_kind == TYPE_STRUCT
            && sym->array_element_struct_name && val->type.struct_name) {
            if (strcmp(sym->array_element_struct_name, val->type.struct_name) != 0) {
                error_add(errors, "<sema>", node->loc.line, node->loc.col,
                          "数组元素类型不匹配: 期望 '%s'，得到 '%s'",
                          sym->array_element_struct_name, val->type.struct_name);
            }
        }
        node->type.kind = TYPE_VOID;
        break;
    }

    case AST_IF_STMT:
        analyze_expr(node->as.if_stmt.cond, scope, errors, a);
        if (node->as.if_stmt.cond->type.kind != TYPE_BOOL &&
            node->as.if_stmt.cond->type.kind != TYPE_ERROR) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col, "if 条件必须是布尔类型");
        }
        analyze_node(node->as.if_stmt.then_block, scope, errors, a);
        if (node->as.if_stmt.else_block) {
            analyze_node(node->as.if_stmt.else_block, scope, errors, a);
        }
        break;

    case AST_WHILE_STMT:
        analyze_expr(node->as.while_stmt.cond, scope, errors, a);
        if (node->as.while_stmt.cond->type.kind != TYPE_BOOL &&
            node->as.while_stmt.cond->type.kind != TYPE_ERROR) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col, "while 条件必须是布尔类型");
        }
        analyze_node(node->as.while_stmt.body, scope, errors, a);
        break;

    case AST_RETURN_STMT:
        if (node->as.return_stmt.expr) {
            analyze_expr(node->as.return_stmt.expr, scope, errors, a);
            node->type.kind = node->as.return_stmt.expr->type.kind;
            TypeKind actual = node->as.return_stmt.expr->type.kind;
            TypeKind expected = current_return_type;
            if (actual != TYPE_ERROR && expected != TYPE_VOID) {
                if (expected == TYPE_STRUCT) {
                    // 结构体返回类型：比较具体类型名
                    const char* actual_name = node->as.return_stmt.expr->type.struct_name;
                    const char* expected_name = current_return_struct_name;
                    if (actual != TYPE_STRUCT || !actual_name || !expected_name ||
                        strcmp(actual_name, expected_name) != 0) {
                        error_add(errors, "<sema>", node->loc.line, node->loc.col,
                                  "返回类型不匹配: 期望 '%s'，得到 '%s'",
                                  expected_name ? expected_name : "struct",
                                  actual_name ? actual_name : type_name(actual));
                    }
                } else if (actual != expected &&
                           !(expected == TYPE_I64 && actual == TYPE_ENUM)) {
                    error_add(errors, "<sema>", node->loc.line, node->loc.col,
                              "返回类型不匹配: 期望 '%s'，得到 '%s'",
                              type_name(expected), type_name(actual));
                }
            }
        } else if (current_return_type != TYPE_VOID) {
            error_add(errors, "<sema>", node->loc.line, node->loc.col,
                      "函数应返回值类型 '%s'",
                      current_return_struct_name ? current_return_struct_name : type_name(current_return_type));
        }
        break;

    case AST_EXPR_STMT:
        analyze_expr(node->as.expr_stmt.expr, scope, errors, a);
        break;

    default:
        analyze_expr(node, scope, errors, a);
        break;
    }
}

void sema_analyze(AstNode* ast, ErrorList* errors, Arena* arena) {
    Scope* global_scope = scope_new(arena, NULL);

    // 注册内置函数
    TypeKind params_i64[] = {TYPE_I64};
    scope_insert_function(global_scope, arena, "print_i64", TYPE_VOID, NULL, params_i64, NULL, 1);
    TypeKind params_f64[] = {TYPE_F64};
    scope_insert_function(global_scope, arena, "print_f64", TYPE_VOID, NULL, params_f64, NULL, 1);
    TypeKind params_bool[] = {TYPE_BOOL};
    scope_insert_function(global_scope, arena, "print_bool", TYPE_VOID, NULL, params_bool, NULL, 1);
    TypeKind params_str[] = {TYPE_STR};
    scope_insert_function(global_scope, arena, "print_str", TYPE_VOID, NULL, params_str, NULL, 1);

    analyze_node(ast, global_scope, errors, arena);
}