package main

import (
	"bufio"
	"bytes"
	"flag"
	"fmt"
	"github.com/knieriem/markdown"
	"html/template"
	"io"
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

var (
	titleFlag    = flag.String(`title`, `goswf`, `site title`)
	subtitleFlag = flag.String(`subtitle`, ``, `site subtitle`)
	dirFlag      = flag.String(`in`, ``, `markdown file tree`)
	ignoreRegExp = flag.String(`ignore`, ``, `ignore regexp`)
	tmplFlag     = flag.String(`tmpl`, ``, `template file`)
	mdParser     = markdown.NewParser(&markdown.Extensions{Smart: true})
	mdExtMatch   = regexp.MustCompile(`\.md$`)
	tmplParser   *template.Template
)

type Navigation struct {
	Name string
	Link string
}

type PageItems struct {
	Title    string
	SubTitle string
	Favicon  string
	CSS      string
	NavItems []Navigation
	Main     template.HTML
}

func main() {
	flag.Parse()
	fi, err := os.Stat(*dirFlag)
	if err != nil || !fi.IsDir() {
		fmt.Fprintln(os.Stderr, `Fatal: -in flag unset or not a directory`)
		flag.Usage()
		os.Exit(1)
	}
	if *tmplFlag == "" {
		fmt.Fprintln(os.Stderr, `Fatal: -tmpl flag unset or not a file`)
		flag.Usage()
		os.Exit(1)
	}

	abs, _ := filepath.Abs(*dirFlag)
	dir, inDir := filepath.Split(abs)
	outDir := filepath.Join(dir, inDir+`.static`)
	if err = os.Chdir(dir); err != nil {
		panic(err)
	}

	if fi, err = os.Stat(outDir); err == nil {
		if err = os.RemoveAll(outDir); err != nil {
			panic(err)
		}
	}

	tmplParser, err = template.ParseFiles(*tmplFlag)
	if err != nil {
		panic(err)
	}

	filepath.Walk(filepath.Base(*dirFlag), mkPage)
	os.Exit(0)
}

func mkPage(srcPath string, info os.FileInfo, err error) error {
	if skip, err := regexp.MatchString(*ignoreRegExp, filepath.Base(srcPath)); err != nil {
		panic(err)
	} else if skip {
		return filepath.SkipDir
	}

	src, err := os.Open(srcPath)
	if err != nil {
		panic(err)
	}

	var writer *bufio.Writer
	if destPath, dest := getDest(srcPath); dest != nil {
		writer = bufio.NewWriter(dest)

		// writer flushes before dest closes
		defer dest.Close()
		defer func() {
			if writer != nil && err == nil {
				err = writer.Flush()
				if err != nil {
					panic(err)
				}
			}
		}()
	} else { // dest will be null if we're iterating over a directory
		if err = os.Mkdir(destPath, 0755); err != nil {
			panic(err)
		}
		return nil
	}

	pageElems := PageItems{
		Title:    *titleFlag,
		SubTitle: *subtitleFlag,
		CSS:      `/style.css`,
	}

	/* XXX: index and navitems
	dir, err := os.Open(filepath.Dir(srcPath))
	if err != nil {
		return err
	} else {
		defer dir.Close()
	}
	names, err := dir.Readdirnames(0)
	if err != nil {
		fmt.Println(err)
	}
	*/

	switch filepath.Ext(srcPath) {
	case `.md`:
		buf := new(bytes.Buffer)
		mdParser.Markdown(src, markdown.ToHTML(buf))
		pageElems.Main = template.HTML(buf.String())
		if err = tmplParser.Execute(writer, pageElems); err != nil {
			panic(err)
		}
	default:
		io.Copy(writer, src)
	}
	return nil
}

func getDest(path string) (destPath string, dest *os.File) {
	parts := strings.Split(path, string(filepath.Separator))
	parts[0] = parts[0] + `.static`
	last := &parts[len(parts)-1]
	*last = mdExtMatch.ReplaceAllLiteralString(*last, `.html`)
	destPath = strings.Join(parts, string(filepath.Separator))
	fi, err := os.Stat(path)
	if err == nil && !fi.IsDir() {
		if dest, err = os.Create(destPath); err != nil {
			panic(err)
		}
	}
	return destPath, dest
}