package downloader

import (
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"os"
	"path"
	"path/filepath"
	"time"
)

const (
	DefaultTimeout = 30 * time.Second
	UserAgent      = "M3U8-Downloader/1.0"
)

type HTTPClient struct {
	client  *http.Client
	headers map[string]string
}

func NewHTTPClient() *HTTPClient {
	return &HTTPClient{
		client: &http.Client{
			Timeout: DefaultTimeout,
		},
		headers: map[string]string{
			"User-Agent": UserAgent,
		},
	}
}

func (c *HTTPClient) SetTimeout(timeout time.Duration) {
	c.client.Timeout = timeout
}

func (c *HTTPClient) SetHeader(key, value string) {
	c.headers[key] = value
}

func (c *HTTPClient) Get(url string) ([]byte, error) {
	return c.GetWithContext(context.Background(), url)
}

func (c *HTTPClient) GetWithContext(ctx context.Context, url string) ([]byte, error) {
	if !ValidateURL(url) {
		return nil, errors.New("invalid URL format")
	}

	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}

	// Set headers
	for key, value := range c.headers {
		req.Header.Set(key, value)
	}

	resp, err := c.client.Do(req)
	if err != nil {
		return nil, fmt.Errorf("request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("HTTP %d: %s", resp.StatusCode, resp.Status)
	}

	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("failed to read response: %w", err)
	}

	return data, nil
}

// Global client instance for convenience functions
var defaultClient = NewHTTPClient()

func FetchPlaylistContent(url string) (string, error) {
	data, err := defaultClient.Get(url)
	if err != nil {
		return "", err
	}
	return string(data), nil
}

func DownloadTSFile(url string, outputDir string) error {
	if err := os.MkdirAll(outputDir, 0755); err != nil {
		return fmt.Errorf("failed to create directory: %w", err)
	}

	fileName := path.Base(url)
	filePath := filepath.Join(outputDir, fileName)
	data, err := defaultClient.Get(url)
	if err != nil {
		return err
	}

	out, err := os.Create(filePath)
	if err != nil {
		return err
	}
	defer out.Close()

	_, err = out.Write(data)
	if err != nil {
		return err
	}
	return nil
}

func FetchPlaylistContentWithContext(ctx context.Context, url string) (string, error) {
	data, err := defaultClient.GetWithContext(ctx, url)
	if err != nil {
		return "", err
	}
	return string(data), nil
}

func SetDefaultTimeout(timeout time.Duration) {
	defaultClient.SetTimeout(timeout)
}

func SetDefaultUserAgent(userAgent string) {
	defaultClient.SetHeader("User-Agent", userAgent)
}