package main

import (
	"bytes"
	"context"
	"database/sql"
	"fmt"
	"log"
	"net/http"
	"os"
	"strconv"
	"time"

	"github.com/joho/godotenv"
	"github.com/yuin/goldmark"
	"github.com/yuin/goldmark/extension"
	"github.com/yuin/goldmark/parser"
	"github.com/yuin/goldmark/renderer/html"
	"paterissa.net/mblog/internal"

	_ "github.com/jackc/pgx/v5/stdlib"
)

var db *sql.DB
var mdParser goldmark.Markdown

func writeErr(w http.ResponseWriter, errcode int, msg string) {
	w.WriteHeader(errcode)
	w.Write([]byte(msg))
	return
}

func mdServe(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		writeErr(w, http.StatusMethodNotAllowed, "Method Not Allowed")
		return
	}
	
	err := r.ParseMultipartForm(4 << 20)
	if err != nil {
		writeErr(w, http.StatusUnprocessableEntity, fmt.Sprintf("Failed to retrieve form data: %v", err))
		return
	}

	var longBuf bytes.Buffer
	var shortBuf bytes.Buffer
	md := r.Form.Get("raw")
	userId := r.Form.Get("user_id")

	shouldCreateShort := len(md) > 255
	
	err = mdParser.Convert([]byte(md), &longBuf)
	if err != nil {
		writeErr(w, http.StatusUnprocessableEntity, fmt.Sprintf("Failed to compile markdown into html: %v", err))
		return
	}
	
	var shortMd string
	if shouldCreateShort {
		shortMd = md[0:249]
		err = mdParser.Convert([]byte(shortMd), &shortBuf)
		
		if err != nil {
			writeErr(w, http.StatusUnprocessableEntity, fmt.Sprintf("Failed to compile markdown into html: %v", err))
			return
		}
	}

	ctx, cancel := context.WithTimeout(r.Context(), 5 * time.Second)
	defer cancel()

	tx, err := db.BeginTx(ctx, nil)
	if err != nil {
		writeErr(w, http.StatusInternalServerError, fmt.Sprintf("Failed to initialize transaction: %v", err))
		return
	}
	defer tx.Rollback()

	stmt, err := tx.PrepareContext(ctx, "INSERT INTO posts (user_id, brief, content) VALUES ($1, $2, $3);")
	if err != nil {
		writeErr(w, http.StatusInternalServerError, fmt.Sprintf("Failed to prepare DB statement: %v", err))
		return
	}
	defer stmt.Close()

	userIdInt, err := strconv.ParseUint(userId, 10, 64)
	if err != nil {
		writeErr(w, http.StatusUnprocessableEntity, fmt.Sprintf("Failed to parse userId: %v\n", err))
		return
	}

	if shouldCreateShort {
		_, err = stmt.ExecContext(ctx, userIdInt, shortBuf.Bytes(), longBuf.Bytes())
	} else {
		_, err = stmt.ExecContext(ctx, userIdInt, longBuf.Bytes(), longBuf.Bytes())
	}

	if err != nil {
		writeErr(w, http.StatusInternalServerError, fmt.Sprintf("Failed to execute statement: %v", err))
		return
	}

	err = tx.Commit()
	if err != nil {
		writeErr(w, http.StatusInternalServerError, fmt.Sprintf("Failed to commit DB transaction: %v", err))
		return
	}
}

func main() {
	err := godotenv.Load()
	if err != nil {
		log.Fatal("Failed to load env")
	}

	mdParser = goldmark.New(
		goldmark.WithExtensions(
			extension.GFM,
			extension.Footnote,
			extension.Typographer,
		),
		goldmark.WithParserOptions(
			parser.WithAutoHeadingID(),
		),
		goldmark.WithRendererOptions(
			html.WithHardWraps(),
		),
	)

	host := os.Getenv("db_host")
	port, err := strconv.ParseUint(os.Getenv("db_port"), 10, 64)
	if err != nil {
		port = 5432
	}
	dbName := os.Getenv("db_name")
	user := os.Getenv("db_user")
	pass := os.Getenv("db_pass")
	connStr := fmt.Sprintf("host=%s port=%d user=%s password=%s dbname=%s sslmode=disable", host, port, user, pass, dbName)

	db, err = sql.Open("pgx", connStr)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Unable to connect to DB: %v\n", err)
		os.Exit(1)
	}
	defer db.Close()

	internal.Migrate(db, os.Getenv("webmaster"), os.Getenv("blog_pass1"), os.Getenv("blog_pass2"))

	router := http.NewServeMux()
	router.HandleFunc("/", mdServe)

	appPort, err := strconv.ParseUint(os.Getenv("parser_port"), 10, 64)
	if err != nil {
		appPort = 5006
	}

	srv := &http.Server{
		Addr: fmt.Sprintf(":%d", appPort),
		Handler: router,
	}

	err = srv.ListenAndServe()
	log.Fatal(err)
}