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"
	"golang.org/x/crypto/bcrypt"

	_ "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, 405, "Method Not Allowed")
		return
	}

	err := r.ParseMultipartForm(4 << 20)
	if err != nil {
		writeErr(w, 500, "Failed to retrieve form data")
		return
	}

	var buf bytes.Buffer

	md := r.PostForm.Get("raw")
	
	err = mdParser.Convert([]byte(md), &buf)
	if err != nil {
		writeErr(w, 500, 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, 500, fmt.Sprintf("Failed to initialize transaction: %v", err))
		return
	}
	defer tx.Rollback()

	stmt, err := tx.PrepareContext(ctx, "INSERT INTO posts (name, content) VALUES ($1, $2);")
	if err != nil {
		writeErr(w, 500, fmt.Sprintf("Failed to prepare DB statement: %v", err))
		return
	}
	defer stmt.Close()

	_, err = stmt.ExecContext(ctx, os.Getenv("webmaster"), buf.Bytes())
	if err != nil {
		writeErr(w, 500, fmt.Sprintf("Failed to execute statement: %v", err))
		return
	}

	err = tx.Commit()
	if err != nil {
		writeErr(w, 500, fmt.Sprintf("Failed to commit DB transaction: %v", err))
	}

	w.WriteHeader(200)
	w.Write([]byte("Successfully parsed and stored markdown"))
}

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 := "localhost"
	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()

	_, table_check := db.Query("SELECT * FROM posts;")
	if table_check != nil {
		_, err = db.Exec("CREATE TABLE posts (id SERIAL PRIMARY KEY, name VARCHAR(50) NOT NULL, time DATE DEFAULT CURRENT_DATE, content TEXT NOT NULL);")
		if err != nil {
			fmt.Fprintf(os.Stderr, "Unable to create posts table: %v\n", err)
			os.Exit(1)
		}
	}

	webmaster := os.Getenv("webmaster")
	passOne := os.Getenv("blog_pass1")
	passTwo := os.Getenv("blog_pass2")

	_, table_check = db.Query("SELECT * FROM users;")
	if table_check != nil {
		_, err = db.Exec("CREATE TABLE logins (id SERIAL PRIMARY KEY, name VARCHAR(50) NOT NULL, time DATE DEFAULT CURRENT_DATE, pass_one TEXT NOT NULL, pass_two TEXT NOT NULL);")
		if err != nil {
			fmt.Fprintf(os.Stderr, "Unable to create logins table: %v\n", err)
			os.Exit(1)
		}

		hashOne, errHashOne := bcrypt.GenerateFromPassword([]byte(passOne), 12)
		hashTwo, errHashTwo := bcrypt.GenerateFromPassword([]byte(passTwo), 12)
		if errHashOne != nil || errHashTwo != nil {
			fmt.Fprintf(os.Stderr, "Failed to hash password")
			os.Exit(1)
		}

		_, err = db.Exec(fmt.Sprintf("INSERT INTO logins (name, pass_one, pass_two) VALUES ('%s', '%s', '%s');", webmaster, hashOne, hashTwo))
		if err != nil {
			fmt.Fprintf(os.Stderr, "Unable to add webmaster to logins table: %v\n", err)
			os.Exit(1)
		}
	}

	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)
}