package main

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"strings"

	"go.uber.org/zap"
)

func registerAPI(mux *http.ServeMux, sqlite *sqliteStore, logger *zap.Logger) {
	mux.HandleFunc("/api/v1/flashcards", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			http.Error(w, `{"error":"method not allowed"}`, http.StatusMethodNotAllowed)
			return
		}

		ids, err := sqlite.listAllPublicIDs(r.Context())
		if err != nil {
			logger.Error("list flashcards", zap.Error(err))
			http.Error(w, `{"error":"internal error"}`, http.StatusInternalServerError)
			return
		}

		urls := make([]string, 0, len(ids))
		for _, id := range ids {
			urls = append(urls, fmt.Sprintf("/api/v1/flashcards/%d", id))
		}

		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string][]string{"flashcards": urls})
	})

	mux.HandleFunc("/api/v1/flashcards/", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			http.Error(w, `{"error":"method not allowed"}`, http.StatusMethodNotAllowed)
			return
		}

		segments := strings.Split(strings.TrimPrefix(r.URL.Path, "/api/v1/flashcards/"), "/")
		if len(segments) == 0 || segments[0] == "" {
			http.Error(w, `{"error":"not found"}`, http.StatusNotFound)
			return
		}

		publicID, err := strconv.ParseInt(segments[0], 10, 64)
		if err != nil {
			http.Error(w, `{"error":"invalid id"}`, http.StatusBadRequest)
			return
		}

		if len(segments) >= 2 && segments[1] != "" {
			version, err := strconv.Atoi(segments[1])
			if err != nil {
				http.Error(w, `{"error":"invalid version"}`, http.StatusBadRequest)
				return
			}
			e, err := sqlite.getByPublicIDAndVersion(r.Context(), publicID, version)
			writeEntry(w, e, err)
			return
		}

		e, err := sqlite.getLatestByPublicID(r.Context(), publicID)
		writeEntry(w, e, err)
	})
}

func writeEntry(w http.ResponseWriter, e *entry, err error) {
	if err != nil {
		http.Error(w, `{"error":"internal error"}`, http.StatusInternalServerError)
		return
	}
	if e == nil {
		http.Error(w, `{"error":"not found"}`, http.StatusNotFound)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(e)
}