package api

import (
	"encoding/json"
	"log"
	"net/http"
	"strings"
	"time"

	"bookmarkmanager/backend/internal/store"
)

// Handler serves the userscript-facing JSON bookmark API.
type Handler struct {
	Store *store.Store
}

func writeJSON(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	if v != nil {
		if err := json.NewEncoder(w).Encode(v); err != nil {
			log.Printf("encode response: %v", err)
		}
	}
}

// List returns all bookmarks. GET /bookmarks
func (h *Handler) List(w http.ResponseWriter, r *http.Request) {
	items, err := h.Store.List()
	if err != nil {
		log.Printf("list: %v", err)
		http.Error(w, "internal error", http.StatusInternalServerError)
		return
	}
	writeJSON(w, http.StatusOK, items)
}

// Put upserts one bookmark. PUT /bookmarks/{key}
func (h *Handler) Put(w http.ResponseWriter, r *http.Request) {
	key := r.PathValue("key")
	if key == "" {
		http.Error(w, "missing key", http.StatusBadRequest)
		return
	}

	var b store.Bookmark
	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 1<<16)).Decode(&b); err != nil {
		http.Error(w, "invalid JSON body", http.StatusBadRequest)
		return
	}

	// Path key is authoritative; derive site/series_id from it when the body
	// omits them so the stored row is always self-consistent.
	b.Key = key
	if b.Site == "" || b.SeriesID == "" {
		if site, series, ok := strings.Cut(key, ":"); ok {
			if b.Site == "" {
				b.Site = site
			}
			if b.SeriesID == "" {
				b.SeriesID = series
			}
		}
	}

	// An empty status is "no opinion" and Upsert keeps the stored bucket.
	// Finishing a series is a web-UI decision, so the JSON API refuses it
	// rather than trusting every client to leave it alone.
	switch b.Status {
	case "", store.StatusReading, store.StatusArchived:
	case store.StatusFinished:
		http.Error(w, "status "+store.StatusFinished+" can only be set from the web UI",
			http.StatusBadRequest)
		return
	default:
		http.Error(w, "invalid status", http.StatusBadRequest)
		return
	}

	// Same rule as status: empty means "keep the stored value". An unknown
	// value is a client bug, not something to silently coerce to manga.
	switch b.Kind {
	case "", store.KindManga, store.KindNovel:
	default:
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid kind"})
		return
	}

	// Candidate timestamp, not a decision: Upsert keeps the stored one unless
	// reading progress actually moved. Any client value is ignored.
	b.UpdatedAt = time.Now().UnixMilli()

	stored, err := h.Store.Upsert(b)
	if err != nil {
		log.Printf("upsert: %v", err)
		http.Error(w, "internal error", http.StatusInternalServerError)
		return
	}
	// Echo the stored row: clients adopt this as their cached copy, so it must
	// carry the authoritative updated_at rather than the candidate above.
	writeJSON(w, http.StatusOK, stored)
}

// Delete removes one bookmark. DELETE /bookmarks/{key}
func (h *Handler) Delete(w http.ResponseWriter, r *http.Request) {
	key := r.PathValue("key")
	if key == "" {
		http.Error(w, "missing key", http.StatusBadRequest)
		return
	}
	if err := h.Store.Delete(key); err != nil {
		log.Printf("delete: %v", err)
		http.Error(w, "internal error", http.StatusInternalServerError)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// Healthz answers the unauthenticated liveness check. GET /healthz
func Healthz(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/plain")
	w.WriteHeader(http.StatusOK)
	_, _ = w.Write([]byte("ok"))
}