package main

import (
	"context"
	"database/sql"
	"embed"
	"encoding/json"
	"fmt"
	"github.com/num30/config"
	"github.com/pressly/goose/v3"
	"go.uber.org/zap"
	"io"
	"net/http"
	"strings"

	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
	_ "github.com/mattn/go-sqlite3"
	"golang.org/x/oauth2"
)

//go:embed static/*
var staticFiles embed.FS

//go:embed database/sqlite/migration/*.sql
var sqliteMigrations embed.FS

type OAuthConfig struct {
	ClientID     string `config:"client_id"`
	ClientSecret string `config:"client_secret"`
	AuthURL      string `config:"auth_url"`
	TokenURL     string `config:"token_url"`
	UserInfoURL  string `config:"userinfo_url"`
}

type DBConfig struct {
	Driver   string `config:"driver"`
	Host     string `config:"host"`
	Port     int    `config:"port"`
	User     string `config:"user"`
	Password string `config:"password"`
	DBName   string `config:"dbname"`
}

type Config struct {
	Env      string `config:"env"`
	Loglevel string `config:"loglevel"`
	Server   struct {
		Port int `config:"port"`
	} `config:"server"`
	OAuth OAuthConfig `config:"oauth"`
	DB    DBConfig    `config:"db"`
}

var (
	oauthConfig *oauth2.Config
	cfg         Config
	logger      *zap.Logger
)

var db *sql.DB

func main() {
	// Use the global cfg variable instead of declaring a new one
	cfgReader := config.NewConfReader("config").WithSearchDirs("./", ".")
	cfgErr := cfgReader.Read(&cfg)

	zapcfg := zap.NewProductionConfig()
	if cfg.Env == "dev" {
		zapcfg = zap.NewDevelopmentConfig()
	}
	logger, err := zapcfg.Build()
	if err != nil {
		panic(fmt.Sprintf("Failed to initialize logger: %v", err))
	}
	defer logger.Sync()

	if cfgErr != nil {
		logger.Fatal("Failed to load config", zap.Error(cfgErr))
	}

	logger.Info("Loaded config", zap.Any("config", cfg))

	// Initialize OAuth2
	oauthConfig = &oauth2.Config{
		ClientID:     cfg.OAuth.ClientID,
		ClientSecret: cfg.OAuth.ClientSecret,
		Endpoint: oauth2.Endpoint{
			AuthURL:  cfg.OAuth.AuthURL,
			TokenURL: cfg.OAuth.TokenURL,
		},
		RedirectURL: fmt.Sprintf("http://localhost:%d/oauth/callback", cfg.Server.Port),
		Scopes:      []string{"profile", "email"},
	}
	fmt.Println(oauthConfig)

	// Initialize database connection
	var dsn string
	if cfg.DB.Driver == "sqlite3" {
		// For SQLite, the DSN is just the path to the database file
		dsn = cfg.DB.DBName
	} else {
		// For other databases like MySQL, use the standard connection string
		dsn = fmt.Sprintf("%s:%s@tcp(%s:%d)/%s",
			cfg.DB.User, cfg.DB.Password, cfg.DB.Host, cfg.DB.Port, cfg.DB.DBName)
	}

	db, err = sql.Open(cfg.DB.Driver, dsn)
	if err != nil {
		logger.Fatal("Failed to connect to database", zap.Error(err))
	}
	defer db.Close()

	// Test the connection
	if err = db.Ping(); err != nil {
		logger.Fatal("Failed to ping database", zap.Error(err))
	}
	logger.Info("Successfully connected to database", zap.String("driver", cfg.DB.Driver))

	if cfg.DB.Driver == "sqlite3" {
		logger.Info("migrating sqlite database")
		if err := migrateSqlite(db); err != nil {
			logger.Fatal("Failed to migrate database", zap.Error(err))
		}
	}

	// Initialize Echo
	e := echo.New()
	e.Use(middleware.Logger())
	//e.Use(middleware.Recover())
	e.Use(middleware.CORS())

	// OAuth2 routes
	e.GET("/oauth/login", handleOAuthLogin)
	e.GET("/oauth/callback", handleOAuthCallback)

	// Protected API routes
	api := e.Group("/api/v1", oauthMiddleware)
	api.GET("/health", func(c echo.Context) error {
		user := c.Get("user").(map[string]interface{})
		logger.Info("Health check requested", zap.Any("user", user))
		return c.JSON(http.StatusOK, map[string]interface{}{
			"status": "ok",
			"user":   user,
		})
	})

	// Serve static files - must be after API routes
	e.GET("/*", echo.WrapHandler(http.FileServer(http.FS(staticFiles))))

	// Start server
	addr := fmt.Sprintf(":%d", cfg.Server.Port)
	logger.Info("Starting server", zap.Int("port", cfg.Server.Port))
	if err := e.Start(addr); err != nil {
		logger.Fatal("Server error", zap.Error(err))
	}
}

func migrateSqlite(db *sql.DB) error {
	goose.SetBaseFS(sqliteMigrations)

	if err := goose.SetDialect("sqlite3"); err != nil {
		return fmt.Errorf("failed to set db type for migration: %w", err)
	}

	if err := goose.Up(db, "database/sqlite/migration"); err != nil {
		return fmt.Errorf("failed to apply db migrations: %w", err)
	}

	return nil
}

// OAuth login handler
func handleOAuthLogin(c echo.Context) error {
	url := oauthConfig.AuthCodeURL("state", oauth2.AccessTypeOffline)
	logger.Info("Redirecting to OAuth login", zap.String("url", url))
	return c.Redirect(http.StatusFound, url)
}

// OAuth callback handler
func handleOAuthCallback(c echo.Context) error {
	code := c.QueryParam("code")
	if code == "" {
		logger.Warn("Missing OAuth code in callback")
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "missing code"})
	}

	token, err := oauthConfig.Exchange(context.Background(), code)
	if err != nil {
		logger.Error("OAuth token exchange failed", zap.Error(err))
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "failed to exchange token"})
	}

	logger.Info("OAuth token exchanged successfully", zap.String("access_token", token.AccessToken))

	// Return HTML that stores the token and redirects to the main app
	html := fmt.Sprintf(`
	<!DOCTYPE html>
	<html>
	<head>
		<title>Authentication Successful</title>
		<script>
			localStorage.setItem('auth_token', '%s');
			window.location.href = '/';
		</script>
	</head>
	<body>
		<p>Authentication successful. Redirecting...</p>
	</body>
	</html>
	`, token.AccessToken)

	return c.HTML(http.StatusOK, html)
}

// Middleware to enforce OAuth authentication
func oauthMiddleware(next echo.HandlerFunc) echo.HandlerFunc {
	return func(c echo.Context) error {
		authHeader := c.Request().Header.Get("Authorization")
		if authHeader == "" {
			logger.Warn("Missing Authorization header")
			return c.JSON(http.StatusUnauthorized, map[string]string{"error": "missing Authorization header"})
		}

		// Extract Bearer token
		token := strings.TrimPrefix(authHeader, "Bearer ")
		if token == authHeader {
			logger.Warn("Invalid Authorization header format")
			return c.JSON(http.StatusUnauthorized, map[string]string{"error": "invalid Authorization header"})
		}

		// Validate token and fetch user info
		userInfo, err := fetchUserInfo(token)
		if err != nil {
			logger.Error("OAuth token validation failed", zap.Error(err))
			return c.JSON(http.StatusUnauthorized, map[string]string{"error": "invalid token"})
		}

		logger.Info("User authenticated", zap.Any("user", userInfo))
		c.Set("user", userInfo)
		return next(c)
	}
}

// Fetch user info from OAuth provider
func fetchUserInfo(token string) (map[string]interface{}, error) {
	req, err := http.NewRequest("GET", cfg.OAuth.UserInfoURL, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Authorization", "Bearer "+token)

	client := http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("OAuth validation failed: %s", string(body))
	}

	var userInfo map[string]interface{}
	if err := json.NewDecoder(resp.Body).Decode(&userInfo); err != nil {
		return nil, err
	}

	return userInfo, nil
}