package main

import (
	"context"
	"encoding/json"
	"io/fs"
	"log"
	"net/http"
	"strings"

	"git.yetaga.in/alazyreader/library/book"
	"git.yetaga.in/alazyreader/library/config"
	"git.yetaga.in/alazyreader/library/database"
	"git.yetaga.in/alazyreader/library/frontend"
	"github.com/kelseyhightower/envconfig"
)

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

type Library interface {
	GetAllBooks(context.Context) ([]book.Book, error)
}

type Router struct {
	static fs.FS
	lib    Library
}

func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	if req.URL.Path == "/api" {
		APIHandler(r.lib).ServeHTTP(w, req)
		return
	}
	StaticHandler(r.static).ServeHTTP(w, req)
}

func APIHandler(l Library) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		books, err := l.GetAllBooks(r.Context())
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		b, err := json.Marshal(books)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusOK)
		w.Write(b)
		w.Write([]byte("\n"))
	})
}

func StaticHandler(f fs.FS) http.Handler {
	return http.FileServer(http.FS(f))
}

func main() {
	var c config.Config
	err := envconfig.Process("library", &c)
	if err != nil {
		log.Fatalln(err)
	}
	f, err := frontend.Root()
	if err != nil {
		log.Fatalln(err)
	}
	if c.DBUser == "" || c.DBPass == "" || c.DBHost == "" || c.DBPort == "" || c.DBName == "" {
		if c.DBPass != "" { // obscure password
			c.DBPass = c.DBPass[0:max(3, len(c.DBPass))] + strings.Repeat("*", max(0, len(c.DBPass)-3))
		}
		log.Fatalf("vars: %+v", c)
	}
	lib, err := database.NewMySQLConnection(c.DBUser, c.DBPass, c.DBHost, c.DBPort, c.DBName)
	if err != nil {
		log.Fatalln(err)
	}
	err = lib.PrepareDatabase(context.Background())
	if err != nil {
		log.Fatalln(err)
	}
	latest, run, err := lib.RunMigrations(context.Background())
	if err != nil {
		log.Fatalln(err)
	}
	log.Printf("latest migration: %d; migrations run: %d", latest, run)
	r := &Router{
		static: f,
		lib:    lib,
	}
	log.Println("Listening on http://localhost:8080/")
	log.Fatalln(http.ListenAndServe(":8080", r))
}