package main

import (
	"errors"
	"flag"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
)

const (
	header     = "/* This file is automatically generated. */\n"
	srcdirname = "convert"
)

var (
	flagDest   string
	flagSrc    string
	flagQuiet  bool
	flagFormat bool
)

func getSrcdir() (string, error) {
	if flagSrc != "" {
		return flagSrc, nil
	}
	workspace := os.Getenv("BUILD_WORKSPACE_DIRECTORY")
	if workspace != "" {
		return workspace, nil
	}
	exe, err := os.Executable()
	if err != nil {
		return "", err
	}
	return filepath.Dir(filepath.Dir(exe)), nil
}

func mainE() error {
	srcdir, err := getSrcdir()
	if err != nil {
		return fmt.Errorf("could not find source dir: %v", err)
	}
	destdir := flagDest
	if destdir == "" {
		destdir = filepath.Join(srcdir, srcdirname)
	}

	// Read metadata.
	d, err := readData(srcdir)
	if err != nil {
		return err
	}

	// Compile and emit charmap data.
	var hascmap bool
	for _, c := range d.charmaps {
		if len(c.data) != 0 {
			name := "charmap_" + c.filename + ".dat"
			fpath := filepath.Join(destdir, name)
			if !flagQuiet {
				fmt.Fprintln(os.Stderr, "Writing:", fpath)
			}
			if err := ioutil.WriteFile(fpath, c.data, 0666); err != nil {
				return err
			}
			hascmap = true
		}
	}
	if !hascmap {
		return errors.New("could not compile any character map")
	}

	// Write generated output.
	m := genMap(&d)
	if err := writeMap(&d, m, filepath.Join(destdir, "charmap_region.c")); err != nil {
		return err
	}
	if err := writeInfo(&d, filepath.Join(destdir, "charmap_info.c")); err != nil {
		return err
	}
	if err := writeData(&d, filepath.Join(destdir, "charmap_data.c")); err != nil {
		return err
	}
	if err := writeRez(&d, filepath.Join(destdir, "charmap.r")); err != nil {
		return err
	}
	return nil
}

func main() {
	flag.StringVar(&flagDest, "dest", "", "output directory")
	flag.StringVar(&flagSrc, "src", "", "source directory")
	flag.BoolVar(&flagQuiet, "quiet", false, "only output error messages")
	flag.BoolVar(&flagFormat, "format", true, "run clang-format on C output")
	flag.Parse()
	if args := flag.Args(); len(args) != 0 {
		fmt.Fprintf(os.Stderr, "Error: unexpected argument: %q\n", args[0])
		os.Exit(2)
	}
	if err := mainE(); err != nil {
		fmt.Fprintln(os.Stderr, "Error:", err)
		os.Exit(1)
	}
}