package main

import (
	"os"
    "log"
    "fmt"
    "flag"
    "errors"
    "strconv"
    "strings"
    "math/rand"
    "net/http"
    "database/sql"
    "html/template"
    "path/filepath"

    _ "github.com/mattn/go-sqlite3"
)

var errlog *log.Logger	= nil
var db *sql.DB 			= nil

var options Options	= Options{}

var NoSuchComicErr	Err = Err{msg: "no such comic found"}

const dbSquema string = `
CREATE TABLE IF NOT EXISTS comic (
	id          INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
    datetime    DATETIME DEFAULT CURRENT_TIMESTAMP,
    title       CHAR(50),
    image       CHAR(200),
    description TEXT,
    tags        TEXT
);`

type Options struct {
	DBPath			string
	MediaPath		string
	TemplatesPath	string
	Address			string
	Port			int
	Publish			bool
	Title			string
	ImagePath		string
	RunManager		bool
	UploadSize		int64
	SiteURL			string
	SecretPath		string
	Username		string
	Password		string
	CreateUser		bool
	ManagerRoot		string
}

type Comic struct {
    ID				int
	DateTime    	string
	Title       	string
	Image       	string
    Description 	string
    Tags        	string
}

type Context struct {
	Comics		[]struct{
		No			int
		Title		string
		Date		string
		Image		string
	}
	
	Comic 			*Comic
	Current			int
	Previous 		int
	Combo			int
	Next 			int
	First			int
	Last			int
	Title			string
	UserName		string
	SiteURL			string
	Message			string
}

type Err struct {
	msg			string
}

func (o * Options) Parse() error {
    flag.StringVar(&o.DBPath, "d", "./db.sqlite", "Sets path to database file")
    flag.StringVar(&o.MediaPath, "m", "./media/", "Sets path to media directory")
    flag.StringVar(&o.TemplatesPath, "t", "./templates/", "Sets path to templates directory")
    flag.StringVar(&o.Address, "a", "127.0.0.1", "Defines the address the web server will listen to")
    flag.IntVar(&o.Port, "p", 8080, "Defines the port the web server will listen to")
    flag.BoolVar(&o.Publish, "u", false, "Creates new commics. Needs both -i and -l")
    flag.StringVar(&o.Title, "l", "", "Title for new comic")
    flag.StringVar(&o.ImagePath, "i", "", "Image path for new comic")
    flag.BoolVar(&o.RunManager, "r", false, "Runs the content manager instead of the site")
    flag.Int64Var(&o.UploadSize, "z", 10, "Max upload size for posts")
    flag.StringVar(&o.SiteURL, "0", "https://comics.blackram.works", "URL of the site once deployed")
    flag.StringVar(&o.SecretPath, "s", "./secret.key", "Sets path to secret key file")
    flag.StringVar(&o.Username, "w", "", "Username for the new user")
    flag.StringVar(&o.Password, "q", "", "Password for the new user")
    flag.BoolVar(&o.CreateUser, "c", false, "Creates a new user. Needs -w and -q")
    flag.StringVar(&o.ManagerRoot, "o", "manager", "Manager root page")
    
	flag.Parse()
	
	if o.CreateUser {
		o.RunManager = true
	}
	
	if _, err := os.Stat(o.TemplatesPath); errors.Is(err, os.ErrNotExist) {
		log.Fatal(err)
	}
	
	if _, err := os.Stat(o.MediaPath); errors.Is(err, os.ErrNotExist) {
	err := os.Mkdir(o.MediaPath, os.ModePerm)
		if err != nil {
			log.Fatal(err)
		}
	}
	return nil
}

func (e * Err) Error() string {
	return e.msg
}

func (e * Err) With(i string) Err {
	return Err{msg:fmt.Sprintf("%s with %s", e.msg, i)}
}

func (c *Comic) readRow(db * sql.Rows) error {
    return db.Scan(&c.ID, &c.DateTime, &c.Title, &c.Image,
        &c.Description, &c.Tags)
}

func getComic(id int) (*Comic, error) {
	id -= 1

	c := new(Comic)
	nferr := NoSuchComicErr.With(fmt.Sprintf("id \"%d\"", id))

	if id < 0 {
		return c, &nferr
	}
	
    comics, err := allComics()
    if err != nil {
        return c, err
    }
    
    if len(comics) <= id {
		return c, &nferr
    }
    
	*c = comics[id]
    return c, err
}

func readRows(rows *sql.Rows) ([]Comic, error) {
    comics := []Comic{}
    for rows.Next() {
        c := Comic{}
        err := c.readRow(rows)
        if err != nil {
            return comics, nil
        }
        comics = append(comics, c)
    }

    return comics, nil
}

func allComics() ([]Comic, error) {
    rows, err := db.Query("SELECT * FROM comic ORDER BY datetime ASC")
    if err != nil {
        return nil, err
    }
    defer rows.Close()

    return readRows(rows)
}

func executeTemplate(w http.ResponseWriter, name string, data interface{}) error {
	t, err := template.ParseFiles(filepath.Join(options.TemplatesPath, fmt.Sprintf("%s.html", name)))	
	if err != nil {
		return err
	}
	
	tmp := new(strings.Builder)
	err = t.Execute(tmp, data)
	if err != nil {
		return err
	}
	_, err = w.Write([]byte(tmp.String()))
	return err
}

func comicView(w http.ResponseWriter, r * http.Request) {
	var err error
	
	if len(r.URL.Path) > 1 && r.URL.Path[len(r.URL.Path)-1] == '/' {
		r.URL.Path = r.URL.Path[len(r.URL.Path)-2:]
	}
	path := strings.TrimPrefix(r.URL.Path, "/")
	if path == options.ManagerRoot {
		http.Redirect(w, r, managerPath("/index"), http.StatusSeeOther)
		return
	}
	
	if len(path) >= 5 {
		path = path[:5]
	}
	
	defer func() {
		if err != nil {
			errlog.Println(err)
			return404(w,r)
			return
		}
	}()
	
	c := &Comic{}
	context := Context{
		Comics:		nil,
		Comic: 		c,
		Title:		"Black Ram Comics",
	}
	
	i := 1
	if len(path) > 0{
		i, err = strconv.Atoi(path)
		if err != nil {
			return
		}
	}
	context.Current = i

	
	comics, err := allComics()
	if err != nil {
		return500(w,r)
		err = nil
		return
	}
	
	if len(comics) > 0 {
		c, err = getComic(i)
		if err != nil {
			errlog.Println(err)
			return404(w,r)
			err = nil
			return
		}
		
		u, err := c.getAuthor()
		if err == nil {
			context.UserName = u.Name
		}
		context.Comic = c
		context.Title = fmt.Sprintf("Black Ram Comics: %s", c.Title)
	} else {
		context.Comic = nil
	}
	
	context.First = 1
	context.Last = len(comics)
	
	context.Previous = i
	if i > 1 {
		context.Previous = i - 1
	}
	
	context.Next = i
	if i < (len(comics)) {
		context.Next = i + 1
	}
	
	err = executeTemplate(w, "comic", &context)
}

func allView(w http.ResponseWriter, r * http.Request) {
	var err error
	
	defer func() {
		if err != nil {
			errlog.Println(err)
			return500(w,r)
			err = nil
			return
		}
	} ()

	context := Context{
		Comics:		nil,
		Title:		"All Issues",
	}
	
	comics, err := allComics()
	if err != nil {
		return
	}
	
	for i, comic := range comics {
		context.Comics = append(context.Comics, struct {
			No 		int
			Title 	string
			Date	string
			Image	string
		}{
			Title:	comic.Title,
			No:		i+1,
			Date:	comic.DateTime,
			Image:	comic.Image,
		})
	}
	
	err = executeTemplate(w, "comic", &context)
}

func latestView(w http.ResponseWriter, r * http.Request) {
	comics, err := allComics()
	if err != nil {
		return500(w, r)
	}
	
	if len(comics) < 1 {
		return404(w, r)
	} else {
		r.URL.Path = fmt.Sprintf("/%d", len(comics)-1)
		comicView(w, r)
	}
}

func firstView(w http.ResponseWriter, r * http.Request) {
	comics, err := allComics()
	if err != nil {
		return500(w, r)
	}
	
	if len(comics) < 1 {
		return404(w, r)
	} else {
		r.URL.Path = fmt.Sprintf("/0")
		comicView(w, r)
	}
}

func randomView(w http.ResponseWriter, r * http.Request) {
	comics, err := allComics()
	if err != nil {
		errlog.Println(err)
		return500(w, r)
		return
	}
	
	if len(comics) < 1 {
		return404(w, r)
	} else {
		r.URL.Path = fmt.Sprintf("/%d", rand.Intn(len(comics))+1)
		comicView(w, r)
	}
}

// Taken from: https://gist.github.com/hoitomt/c0663af8c9443f2a8294
func logRequest(handler http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		log.Printf("%s %s %s\n", r.RemoteAddr, r.Method, r.URL)
		handler.ServeHTTP(w, r)
	})
}

func returnPlainText(w http.ResponseWriter, t string) error {
	w.Header().Set("Content-Type", "text/plain")
	_, err := w.Write([]byte(t))
	return err
}

func returnError(w http.ResponseWriter, r * http.Request, status int) {
	var err error
	msg := fmt.Sprintf("%d", status)

	w.WriteHeader(status)
	defer func() {
		if err != nil {
			returnPlainText(w, msg)
		}
	}()
	
	t, err := template.ParseFiles(filepath.Join(options.TemplatesPath, "error.html"))
	if err != nil {
		return
	}
	c := struct {
		Code	string
		Title	string
	}{
		Code: 	msg,
		Title:	"BRC: " + msg,
	}
	err = t.Execute(w, &c)
}

func return401(w http.ResponseWriter, r * http.Request) {
	returnError(w, r, http.StatusUnauthorized)
}

func return404(w http.ResponseWriter, r * http.Request) {
	returnError(w, r, http.StatusNotFound)
}

func return500(w http.ResponseWriter, r * http.Request) {
	returnError(w, r, http.StatusInternalServerError)
}

func newComic(title string, image string, description string, tags string) (int, error) {
    res, err := db.Exec("INSERT INTO comic(title, image, description, tags) VALUES(?, ?, ?, ?);",
        title, image, description, tags)
	if err != nil {
		return -1, nil
	}
	
	id := int64(0)
	if id, err = res.LastInsertId(); err != nil {
		return 0, err
  	}
	
    return int(id), err
}

func deleteComic(id int) error {
    _, err := db.Exec("DELETE FROM comic WHERE id = ?;", id)
    return err
}

func main() {
	var err error
	
	errlog = log.New(log.Writer(), "[ERROR] ", log.Flags())
	
	options.Parse()
	
	log.Println("using database path \"" + options.DBPath + "\"")
    db, err = sql.Open("sqlite3", options.DBPath)
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()
	
    _, err = db.Exec(dbSquema)
    if err != nil {
        log.Fatal(err)
    }
    
    if options.Publish {
    	if len(options.ImagePath) < 1 {
    		panic("missing -i")
    	}
    	if len(options.Title) < 1 {
    		panic("missing -l")
    	}
    	_, err = newComic(options.Title, options.ImagePath, "", "")
    	if err != nil {
    		log.Fatal(err)
    	}
    	log.Println(fmt.Sprintf("comic \"%s\" created", options.Title))
    	return
    }
    
    // files
    tPath := string(filepath.Join(options.TemplatesPath, "/static/"))
    log.Println(fmt.Sprintf("using templates path \"%s\"", tPath))
    fs := http.FileServer(http.Dir(tPath))
	http.Handle("/static/", http.StripPrefix("/static/", fs))
	log.Println(fmt.Sprintf("using media path \"%s\"", options.MediaPath))
    fs = http.FileServer(http.Dir(options.MediaPath))
	http.Handle("/media/", http.StripPrefix("/media/", fs))
    
    
    // errors
    http.HandleFunc("/401", return401)
    http.HandleFunc("/404", return404)
    http.HandleFunc("/500", return500)
    
    // manager
    if options.RunManager {
    	err = startManager(options.Address, options.Port, options.DBPath, options.MediaPath)
    	if err != nil {
    		log.Fatal(err)
    	}
    }
    
    // views
    http.HandleFunc("/", comicView)
    http.HandleFunc("/latest", latestView)
    http.HandleFunc("/first", firstView)
    http.HandleFunc("/random", randomView)
    http.HandleFunc("/about", firstView)
    http.HandleFunc("/all", allView)
    http.HandleFunc("/blog", firstView)
    
    uri := fmt.Sprintf("%s:%d", options.Address, options.Port)
    log.Println("listening to http://" + uri)
    log.Fatal(http.ListenAndServe(uri, logRequest(http.DefaultServeMux)))
}