package storage

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

	dcfg "git.misaka.ren/M1saka/docker_backup/internal/config"
)

// WebDAVBackend uploads to a WebDAV server.
type WebDAVBackend struct {
	cfg    *dcfg.WebDAVConfig
	client *http.Client
}

// NewWebDAVBackend creates a configured WebDAV backend.
func NewWebDAVBackend(cfg *dcfg.WebDAVConfig) *WebDAVBackend {
	return &WebDAVBackend{
		cfg: cfg,
		client: &http.Client{
			Timeout: 30 * time.Minute,
		},
	}
}

// Upload implements Backend.
func (w *WebDAVBackend) Upload(ctx context.Context, projectName, localPath string) error {
	baseURL := strings.TrimRight(strings.TrimSpace(w.cfg.URL), "/")
	if baseURL == "" {
		return fmt.Errorf("webdav url is required")
	}

	file, err := os.Open(localPath)
	if err != nil {
		return fmt.Errorf("open: %w", err)
	}
	defer file.Close()

	stat, err := file.Stat()
	if err != nil {
		return fmt.Errorf("stat: %w", err)
	}

	parentURL := baseURL + "/" + projectName
	if err := w.mkcol(ctx, parentURL); err != nil {
		return fmt.Errorf("webdav mkcol %s: %w", parentURL, err)
	}

	remoteURL := parentURL + "/" + filepath.Base(localPath)
	req, err := http.NewRequestWithContext(ctx, http.MethodPut, remoteURL, file)
	if err != nil {
		return fmt.Errorf("new request: %w", err)
	}
	req.ContentLength = stat.Size()
	req.Header.Set("Content-Type", "application/gzip")
	if w.cfg.Username != "" || w.cfg.Password != "" {
		req.SetBasicAuth(w.cfg.Username, w.cfg.Password)
	}

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

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		body, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("webdav put failed: %s (%d): %s", remoteURL, resp.StatusCode, string(body))
	}

	return nil
}

// mkcol creates a WebDAV collection (directory). Existing collections are OK.
func (w *WebDAVBackend) mkcol(ctx context.Context, url string) error {
	req, err := http.NewRequestWithContext(ctx, "MKCOL", url, nil)
	if err != nil {
		return err
	}
	if w.cfg.Username != "" || w.cfg.Password != "" {
		req.SetBasicAuth(w.cfg.Username, w.cfg.Password)
	}
	resp, err := w.client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	// 201 Created is success. Many servers return 405 if collection already exists.
	if resp.StatusCode == http.StatusCreated || resp.StatusCode == http.StatusMethodNotAllowed {
		return nil
	}
	body, _ := io.ReadAll(resp.Body)
	return fmt.Errorf("unexpected status %d: %s", resp.StatusCode, string(body))
}