package config

import (
	"fmt"
	"os"

	"gopkg.in/yaml.v3"
)

// Config 是应用统一配置，对应 config.yaml。
type Config struct {
	Server   ServerConfig   `yaml:"server"`
	Database DatabaseConfig `yaml:"database"`
	JWT      JWTConfig      `yaml:"jwt"`
	Upload   UploadConfig   `yaml:"upload"`
	AI       AIConfig       `yaml:"ai"`
	Env      EnvConfig      `yaml:"env"`
}

type ServerConfig struct {
	Port int `yaml:"port"`
}

type DatabaseConfig struct {
	Driver      string `yaml:"driver"`
	Path        string `yaml:"path"`
	AutoMigrate bool   `yaml:"auto_migrate"`
}

type JWTConfig struct {
	Secret      string `yaml:"secret"`
	ExpireHours int    `yaml:"expire_hours"`
}

type UploadConfig struct {
	Path    string `yaml:"path"`
	MaxSize int64  `yaml:"max_size"`
}

type AIConfig struct {
	APIKey  string `yaml:"api_key"`
	BaseURL string `yaml:"base_url"`
	Model   string `yaml:"model"`
}

type EnvConfig struct {
	Name string `yaml:"name"`
}

// hardcodedAPIKey 内置默认免费 Key（与 config.yaml 一致），
// 保证 CLI 工具在无配置文件时也能开箱即用。
const hardcodedAPIKey = "sk-68FL9xXRrJhxcY5TCGxoaFlQ94oCBioIJhyGfeDMCkCvA0SV"

// DefaultConfig 返回开箱即用的默认配置。
func DefaultConfig() *Config {
	return &Config{
		Server:   ServerConfig{Port: 8080},
		Database: DatabaseConfig{Driver: "sqlite", Path: "./data/app.db", AutoMigrate: true},
		JWT:      JWTConfig{Secret: "change-me-in-production", ExpireHours: 720},
		Upload:   UploadConfig{Path: "uploads", MaxSize: 10 * 1024 * 1024},
		AI: AIConfig{
			APIKey:  hardcodedAPIKey,
			Model:   "agnes-2.0-flash",
			BaseURL: "https://apihub.agnes-ai.com/v1/chat/completions",
		},
		Env: EnvConfig{Name: "dev"},
	}
}

// Load 从 yaml 文件加载配置；文件不存在时使用默认值（便于快速上手）。
// 环境变量覆盖：AGNES_API_KEY → ai.api_key。
func Load(path string) (*Config, error) {
	cfg := DefaultConfig()

	data, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return cfg, nil
		}
		return nil, fmt.Errorf("读取 %s: %w", path, err)
	}
	if err := yaml.Unmarshal(data, cfg); err != nil {
		return nil, fmt.Errorf("解析 %s: %w", path, err)
	}

	// 环境变量覆盖
	if key := os.Getenv("AGNES_API_KEY"); key != "" {
		cfg.AI.APIKey = key
	}
	return cfg, nil
}