package main

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

// Config holds the application configuration.
type Config struct {
	APIKey  string `json:"api_key"`
	Model   string `json:"model"`
	BaseURL string `json:"base_url"`
}

// DefaultConfig returns a Config with sensible defaults.
func DefaultConfig() *Config {
	return &Config{
		Model:   "glm-4.6v-flash",
		BaseURL: "https://open.bigmodel.cn/api/paas/v4/chat/completions",
	}
}

// LoadConfig loads configuration from multiple sources in priority order:
// 1. Command-line --apikey flag (highest)
// 2. ZHIPU_API_KEY environment variable
// 3. config.json in the same directory as the executable
// 4. Default built-in key (lowest)
func LoadConfig(flagKey, configPath string) (*Config, error) {
	cfg := DefaultConfig()

	// Load from config file if it exists (lowest priority)
	if configPath == "" {
		execDir := getExecDir()
		configPath = filepath.Join(execDir, "config.json")
	}

	if data, err := os.ReadFile(configPath); err == nil {
		var fileCfg Config
		if err := json.Unmarshal(data, &fileCfg); err == nil {
			if fileCfg.APIKey != "" {
				cfg.APIKey = fileCfg.APIKey
			}
			if fileCfg.Model != "" {
				cfg.Model = fileCfg.Model
			}
			if fileCfg.BaseURL != "" {
				cfg.BaseURL = fileCfg.BaseURL
			}
		}
	}

	// Override with environment variable
	if envKey := os.Getenv("ZHIPU_API_KEY"); envKey != "" {
		cfg.APIKey = envKey
	}

	// Highest priority: command-line flag
	if flagKey != "" {
		cfg.APIKey = flagKey
	}

	if cfg.APIKey == "" {
		return cfg, fmt.Errorf("API key not configured. Set it via:\n" +
			"  1. --apikey flag\n" +
			"  2. ZHIPU_API_KEY environment variable\n" +
			"  3. config.json file in the tools directory")
	}

	return cfg, nil
}

// SaveConfigFile saves config to a JSON file.
func SaveConfigFile(path, apiKey string) error {
	cfg := DefaultConfig()
	cfg.APIKey = apiKey

	data, err := json.MarshalIndent(cfg, "", "  ")
	if err != nil {
		return err
	}

	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
		return err
	}

	return os.WriteFile(path, data, 0600)
}

func getExecDir() string {
	execPath, err := os.Executable()
	if err != nil {
		return "."
	}
	return filepath.Dir(execPath)
}

// MaskKey masks the API key for safe display, showing only first 8 and last 4 chars.
func MaskKey(key string) string {
	if len(key) <= 12 {
		return strings.Repeat("*", len(key))
	}
	return key[:8] + "..." + key[len(key)-4:]
}