package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"
	"runtime/debug"
	"strings"

	"github.com/alecthomas/chroma/v2"
	"github.com/alecthomas/chroma/v2/formatters/html"
	"github.com/alecthomas/chroma/v2/lexers"
	"github.com/alecthomas/chroma/v2/styles"
	"github.com/niklasfasching/go-org/blorg"
	"github.com/niklasfasching/go-org/org"
)

var usage = `Usage: go-org COMMAND [ARGS]...
Commands:
- render [FILE] FORMAT
  FORMAT: org, html, html-chroma
  Instead of specifying a file, org mode content can also be passed on stdin
- blorg
  - blorg init
  - blorg build
  - blorg serve
`

func main() {
	log.SetFlags(0)
	if len(os.Args) < 2 {
		log.Fatal(usage)
	}
	switch cmd, args := os.Args[1], os.Args[2:]; cmd {
	case "render":
		render(args)
	case "blorg":
		runBlorg(args)
	case "version":
		printVersion()
	default:
		log.Fatal(usage)
	}
}

func runBlorg(args []string) {
	if len(args) == 0 {
		log.Fatal(usage)
	}
	switch strings.ToLower(args[0]) {
	case "init":
		if _, err := os.Stat(blorg.DefaultConfigFile); !os.IsNotExist(err) {
			log.Fatalf("%s already exists", blorg.DefaultConfigFile)
		}
		if err := ioutil.WriteFile(blorg.DefaultConfigFile, []byte(blorg.DefaultConfig), os.ModePerm); err != nil {
			log.Fatal(err)
		}
		if err := os.MkdirAll("content", os.ModePerm); err != nil {
			log.Fatal(err)
		}
		log.Println("./blorg.org and ./content/ created. Please adapt ./blorg.org")
	case "build":
		config, err := blorg.ReadConfig(blorg.DefaultConfigFile)
		if err != nil {
			log.Fatal(err)
		}
		if err := config.Render(); err != nil {
			log.Fatal(err)
		}
		log.Println("blorg build finished")
	case "serve":
		config, err := blorg.ReadConfig(blorg.DefaultConfigFile)
		if err != nil {
			log.Fatal(err)
		}
		log.Fatal(config.Serve())
	default:
		log.Fatal(usage)
	}
}

func render(args []string) {
	r, path, format := io.Reader(nil), "", ""
	if fi, err := os.Stdin.Stat(); err != nil {
		log.Fatal(err)
	} else if len(args) == 2 {
		f, err := os.Open(args[0])
		if err != nil {
			log.Fatal(err)
		}
		defer f.Close()
		r, path, format = f, args[0], args[1]
	} else if fi.Mode()&os.ModeCharDevice == 0 {
		r, path, format = os.Stdin, "./STDIN", args[0]
	} else {
		log.Fatal(usage)
	}
	d := org.New().Parse(r, path)
	write := func(w org.Writer) {
		out, err := d.Write(w)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Fprint(os.Stdout, out)
	}
	switch strings.ToLower(format) {
	case "org":
		write(org.NewOrgWriter())
	case "html":
		write(org.NewHTMLWriter())
	case "html-chroma":
		writer := org.NewHTMLWriter()
		writer.HighlightCodeBlock = highlightCodeBlock
		write(writer)
	default:
		log.Fatal(usage)
	}
}

func highlightCodeBlock(source, lang string, inline bool) string {
	var w strings.Builder
	l := lexers.Get(lang)
	if l == nil {
		l = lexers.Fallback
	}
	l = chroma.Coalesce(l)
	it, _ := l.Tokenise(nil, source)
	_ = html.New().Format(&w, styles.Get("friendly"), it)
	if inline {
		return `<div class="highlight-inline">` + "\n" + w.String() + "\n" + `</div>`
	}
	return `<div class="highlight">` + "\n" + w.String() + "\n" + `</div>`
}

func printVersion() {
	bi, ok := debug.ReadBuildInfo()
	if !ok {
		log.Fatal("not build info available")
	}
	revision, modified := "", false
	for _, s := range bi.Settings {
		if s.Key == "vcs.revision" {
			revision = s.Value
		} else if s.Key == "vcs.modified" {
			modified = s.Value == "true"
		}
	}
	log.Printf("%s (modified: %v)", revision, modified)
}