package main

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

	"github.com/BurntSushi/toml"
)

type Server struct {
	port       string
	contentDir string
	outputDir  string
	serve      bool
	generator  *Generator
}

func NewServer(port, contentDir, outputDir string, serve bool, g *Generator) *Server {
	return &Server{
		port:       port,
		contentDir: contentDir,
		outputDir:  outputDir,
		serve:      serve,
		generator:  g,
	}
}

func (s *Server) Listen() error {
	mux := http.NewServeMux()
	mux.HandleFunc("GET /upload",  s.handleUploadPage)
	mux.HandleFunc("POST /upload", s.handleUpload)
	mux.HandleFunc("GET /health", func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "ok")
	})

	if s.serve {
		// Serve the generated site on the same port — for local development only.
		// In production nginx handles this and the server binds to localhost.
		mux.Handle("/", http.FileServer(http.Dir(s.outputDir)))
		log.Printf("gallery:  http://localhost:%s", s.port)
		log.Printf("upload:   http://localhost:%s/upload", s.port)
		return http.ListenAndServe(":"+s.port, mux)
	}

	log.Printf("upload API on 127.0.0.1:%s", s.port)
	return http.ListenAndServe("127.0.0.1:"+s.port, mux)
}

func (s *Server) handleUploadPage(w http.ResponseWriter, r *http.Request) {
	data, err := assets.ReadFile("templates/upload.html")
	if err != nil {
		http.Error(w, "not found", http.StatusNotFound)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.Write(data)
}

// handleUpload accepts multipart/form-data with fields:
//
//	image    — the image file (jpg or png)
//	caption  — human-readable caption (optional, defaults to filename)
//	date     — YYYY-MM-DD (optional, defaults to today)
func (s *Server) handleUpload(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseMultipartForm(32 << 20); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}

	file, header, err := r.FormFile("image")
	if err != nil {
		http.Error(w, "missing 'image' field", http.StatusBadRequest)
		return
	}
	defer file.Close()

	ext := strings.ToLower(filepath.Ext(header.Filename))
	if ext != ".jpg" && ext != ".jpeg" && ext != ".png" {
		http.Error(w, "only jpg and png are accepted", http.StatusBadRequest)
		return
	}

	caption := r.FormValue("caption")
	dateStr := r.FormValue("date")
	if dateStr == "" {
		dateStr = time.Now().Format("2006-01-02")
	}
	if caption == "" {
		caption = strings.TrimSuffix(header.Filename, ext)
	}

	slug := sanitiseSlug(strings.TrimSuffix(header.Filename, ext))
	if slug == "" {
		slug = fmt.Sprintf("photo-%d", time.Now().UnixMilli())
	}
	imgPath  := filepath.Join(s.contentDir, slug+ext)
	tomlPath := filepath.Join(s.contentDir, slug+".toml")

	out, err := os.Create(imgPath)
	if err != nil {
		log.Printf("create %s: %v", imgPath, err)
		http.Error(w, "could not save image", http.StatusInternalServerError)
		return
	}
	defer out.Close()
	if _, err := io.Copy(out, file); err != nil {
		http.Error(w, "could not write image", http.StatusInternalServerError)
		return
	}

	tf, err := os.Create(tomlPath)
	if err != nil {
		log.Printf("create %s: %v", tomlPath, err)
		http.Error(w, "could not save metadata", http.StatusInternalServerError)
		return
	}
	defer tf.Close()
	if err := toml.NewEncoder(tf).Encode(PhotoMeta{Caption: caption, Date: dateStr}); err != nil {
		http.Error(w, "could not write metadata", http.StatusInternalServerError)
		return
	}

	// Build() is mutex-guarded so calling it here and from the watcher is safe.
	go func() {
		if err := s.generator.Build(); err != nil {
			log.Printf("rebuild after upload: %v", err)
		}
	}()

	w.WriteHeader(http.StatusCreated)
	fmt.Fprintf(w, "uploaded %s\n", slug+ext)
}

// sanitiseSlug returns a filesystem- and URL-safe version of s.
func sanitiseSlug(s string) string {
	var b strings.Builder
	for _, r := range strings.ToLower(s) {
		switch {
		case r >= 'a' && r <= 'z', r >= '0' && r <= '9', r == '-':
			b.WriteRune(r)
		case r == ' ', r == '_':
			b.WriteRune('-')
		}
	}
	return b.String()
}