package main

import (
	"bytes"
	"context"
	"embed"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"io/fs"
	"net/http"
	"net/url"
	"os"
	"path"
	"regexp"
	"time"

	"log/slog"

	"go.balki.me/anyhttp"
	"go.balki.me/anyhttp/idle"
	"go.balki.me/collage-maker/collage"
)

var (
	collageDir      string
	photosDir       string
	devMode         bool
	collageNameGen  *nameGen
	imagesDirFs     fs.FS
	listenAddr      string
	photoPrismURL   *url.URL
	photoPrismToken string

	//go:embed web
	webFS embed.FS
)

func main() {
	var ppURL string

	flag.StringVar(&collageDir, "collages-dir", "collages", "Sets the collages dir")
	flag.StringVar(&photosDir, "photos-dir", "photos", "Cache directory for downloaded photos")
	flag.BoolVar(&devMode, "dev", false, "Serve local assets during development")
	flag.StringVar(&listenAddr, "addr", "127.0.0.1:8767", "Web listen address, see https://pkg.go.dev/go.balki.me/anyhttp#readme-address-syntax")
	flag.StringVar(&ppURL, "pp-url", "", "Base url for photoprism")
	flag.StringVar(&photoPrismToken, "pp-token", "", "API token for photoprism")

	flag.Parse()

	photoPrismURL = func() *url.URL {
		photoPrismURL, err := url.Parse(ppURL)
		if err != nil {
			panic(err)
		}
		return photoPrismURL
	}()
	collageNameGen = NewNameGen()
	imagesDirFs = os.DirFS(photosDir)
	collagesPath := "collages"
	photosPath := "photos"

	addFileServer := func(path, dir string) {
		httpFileServer := http.FileServer(http.Dir(dir))
		http.Handle("/"+path+"/", http.StripPrefix("/"+path, httpFileServer))
	}

	addFileServer(collagesPath, collageDir)
	addFileServer(photosPath, photosDir)

	if devMode {
		httpFileServer := http.FileServer(http.Dir("web"))
		http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
			w.Header().Add("Cache-Control", "no-cache")
			httpFileServer.ServeHTTP(w, r)
		})
	} else {
		indexModTime := time.Now()
		indexHTML := func() io.ReadSeeker {
			indexHTMLContent, err := webFS.ReadFile("web/index.html")
			if err != nil {
				panic(err)
			}
			devOnlyRegex := regexp.MustCompile("\n[^\n]*<!-- DEVONLY[^\n]*")
			return bytes.NewReader(devOnlyRegex.ReplaceAllLiteral(indexHTMLContent, nil))
		}()
		httpFileServer := func() http.Handler {
			webrootFs, err := fs.Sub(webFS, "web")
			if err != nil {
				panic(err)
			}
			return http.FileServer(http.FS(webrootFs))
		}()
		http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
			if r.URL.Path == "/" {
				http.ServeContent(w, r, "index.html", indexModTime, indexHTML)
			} else {
				httpFileServer.ServeHTTP(w, r)
			}
		})
	}

	http.HandleFunc("/make-collage", func(w http.ResponseWriter, r *http.Request) {
		collageReq := collage.Request{}
		body, err := io.ReadAll(r.Body)
		if err != nil {
			slog.Error("failed to read request body", "error", err)
			w.WriteHeader(http.StatusInternalServerError)
			return
		}
		if err := json.Unmarshal(body, &collageReq); err != nil {
			slog.Error("failed to unmarshal json request", "error", err)
			w.WriteHeader(http.StatusInternalServerError)
			return
		}
		collageFilePath, err := MakeCollage(&collageReq)
		if err != nil {
			slog.Error("failed to make collage", "error", err)
			w.WriteHeader(http.StatusInternalServerError)
			return
		}
		if _, err := w.Write([]byte(collageFilePath)); err != nil {
			slog.Error("Failed to write collageFile", "error", err)
		}
	})

	http.HandleFunc("/get-albums", func(w http.ResponseWriter, r *http.Request) {
		albums, err := GetAlbums()
		if err != nil {
			slog.Error("failed to get albums", "error", err)
			w.WriteHeader(http.StatusInternalServerError)
			return
		}
		jData, err := json.Marshal(albums)
		if err != nil {
			slog.Error("failed to marshal albums", "error", err)
			w.WriteHeader(http.StatusInternalServerError)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		w.Write(jData)
	})

	http.HandleFunc("/load-photos/{albumID}", func(w http.ResponseWriter, r *http.Request) {
		albumID := r.PathValue("albumID")
		photos, err := LoadPhotos(albumID)
		if err != nil {
			slog.Error("failed to load photos", "error", err, "album", albumID)
			w.WriteHeader(http.StatusInternalServerError)
			return
		}
		photoURLs := []string{}
		for _, photo := range photos {
			photoURLs = append(photoURLs, fmt.Sprintf("/%s/%s.jpg", photosPath, photo.FileUID))
		}
		go func() {
			for _, photo := range photos {
				_, err := DownloadPhoto(&photo)
				if err != nil {
					slog.Error("failed to download photo", "error", err, "album", albumID, "photoID", photo.FileUID)
				}
			}
		}()

		jData, err := json.Marshal(photoURLs)
		if err != nil {
			slog.Error("failed to marshal photoURLs", "error", err)
			w.WriteHeader(http.StatusInternalServerError)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		w.Write(jData)
	})

	addrType, server, done, err := anyhttp.Serve(listenAddr, idle.WrapHandler(nil))
	if err != nil {
		slog.Error("anyhttp Serve failed", "error", err)
	}

	if addrType == anyhttp.SystemdFD {
		if err := idle.Wait(30 * time.Minute); err != nil {
			slog.Error("Failed to wait for idler", "error", err)
		}
		ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute) // Don't want any stuck connections
		defer cancel()
		if err := server.Shutdown(ctx); err != nil {
			slog.Error("http server Shutdown failed", "error", err)
		}
	} else {
		<-done
	}
}

func MakeCollage(req *collage.Request) (string, error) {
	collageFile := fmt.Sprintf("collage-%s.jpg", collageNameGen.Next())
	out, err := os.Create(path.Join(collageDir, collageFile))
	if err != nil {
		return "", fmt.Errorf("failed to create collage output file, err: %w", err)
	}
	defer out.Close()
	if err := collage.Make(req, imagesDirFs, out); err != nil {
		return "", fmt.Errorf("failed to make collage, err: %w", err)
	}
	return collageFile, nil
}

type Album struct {
	Title string `json:"Title"`
	UID   string `json:"UID"`
}

func GetAlbums() ([]Album, error) {
	albumURL := func() string {
		u := *photoPrismURL
		u.Path = "/api/v1/albums"
		v := url.Values{}
		v.Add("count", "20")
		v.Add("type", "album")
		u.RawQuery = v.Encode()
		return u.String()
	}()

	req, err := http.NewRequest("GET", albumURL, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", photoPrismToken))
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}

	respBytes, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	albums := []Album{}

	err = json.Unmarshal(respBytes, &albums)
	if err != nil {
		return nil, err
	}

	return albums, nil
}

type Photo struct {
	Hash    string `json:"Hash"`
	FileUID string `json:"FileUID"`
}

func LoadPhotos(albumID string) ([]Photo, error) {
	loadPhotosURL := func() string {
		u := *photoPrismURL
		u.Path = "/api/v1/photos"
		v := url.Values{}
		v.Add("count", "50")
		v.Add("s", albumID)
		v.Add("merged", "true")
		v.Add("video", "false")
		u.RawQuery = v.Encode()
		return u.String()

	}()

	req, err := http.NewRequest("GET", loadPhotosURL, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", photoPrismToken))
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}
	respBytes, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	photos := []Photo{}
	err = json.Unmarshal(respBytes, &photos)
	if err != nil {
		return nil, err
	}

	return photos, nil
}

func DownloadPhoto(photo *Photo) (string, error) {
	photoPath := path.Join(photosDir, fmt.Sprintf("%s.jpg", photo.FileUID))
	_, err := os.Stat(photoPath)
	if err == nil {
		return photoPath, nil
	} else if !os.IsNotExist(err) {
		return "", err
	}
	out, err := os.Create(photoPath)
	if err != nil {
		return "", fmt.Errorf("failed to create collage output file, err: %w", err)
	}
	defer out.Close()
	downloadPhotoURL := func() string {
		u := *photoPrismURL
		u.Path = fmt.Sprintf("/api/v1/dl/%s", photo.Hash)
		return u.String()
	}()
	req, err := http.NewRequest("GET", downloadPhotoURL, nil)
	if err != nil {
		return "", err
	}
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", photoPrismToken))
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return "", err
	}

	_, err = io.Copy(out, resp.Body)
	if err != nil {
		return "", err
	}

	return photoPath, nil
}