package main

import (
	"bytes"
	"embed"
	"errors"
	"flag"
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
	"text/template"
	"unicode"

	"git.eidonix.com/eidonix/cletus-plugins/sdk/manifest"
)

//go:embed all:template
var templateFS embed.FS

const sdkModule = "git.eidonix.com/eidonix/cletus-plugins/sdk"

type templateData struct {
	ID, Publisher, Name, Title, Short, Module, SDKModule, SDKVersion string
}

func runNew(args []string) error {
	fs := flag.NewFlagSet("new", flag.ContinueOnError)
	sdkDir := fs.String("sdk-dir", "", "use a local copy of the SDK (for developing the SDK itself)")
	if err := fs.Parse(args); err != nil {
		return err
	}
	if fs.NArg() < 1 || fs.NArg() > 2 {
		return errors.New("usage: cletus-plugin new <publisher>.<name> [folder]")
	}
	id := fs.Arg(0)
	probe := manifest.Plugin{ID: id, Name: "x", Description: "x", Version: "0.1.0", MinAppVersion: "0.5.0", HostAPI: manifest.HostAPI}
	if errs := probe.Validate(); len(errs) > 0 {
		return errs[0]
	}
	publisher, name, _ := strings.Cut(id, ".")
	dir := name
	if fs.NArg() == 2 {
		dir = fs.Arg(1)
	}
	if _, err := os.Stat(dir); err == nil {
		return fmt.Errorf("%s already exists", dir)
	}
	data := templateData{ID: id, Publisher: publisher, Name: name, Title: title(name),
		Short: strings.ReplaceAll(name, "-", "_"), Module: publisher + ".plugins/" + name,
		SDKModule: sdkModule, SDKVersion: sdkVersion}
	if err := writeTemplate(dir, data); err != nil {
		return err
	}
	fmt.Printf("Created %s in %s.\n", id, dir)

	if *sdkDir != "" {
		abs, err := filepath.Abs(*sdkDir)
		if err != nil {
			return err
		}
		// Only for developing the SDK: check refuses replace directives.
		if out, err := goRun(dir, goEnv("", ""), "mod", "edit", "-replace", sdkModule+"="+abs); err != nil {
			return fmt.Errorf("go mod edit: %s", out)
		}
	}
	for _, step := range [][]string{{"mod", "tidy"}, {"mod", "vendor"}} {
		if out, err := goRun(dir, goEnv("", ""), step...); err != nil {
			return fmt.Errorf("go %s failed. Fix the problem below and run it in %s yourself:\n%s", strings.Join(step, " "), dir, out)
		}
	}
	fmt.Printf("\nNext:\n  cd %s\n  cletus-plugin check\n  cletus-plugin run tools\n  cletus-plugin run invoke %s_count_lines '{\"path\":\"sample.txt\"}'\n", dir, data.Short)
	return nil
}

func writeTemplate(dir string, data templateData) error {
	return fs.WalkDir(templateFS, "template", func(path string, d fs.DirEntry, err error) error {
		if err != nil || d.IsDir() {
			return err
		}
		rel := strings.TrimPrefix(path, "template/")
		rel = strings.TrimSuffix(rel, ".tmpl")
		rel = strings.ReplaceAll(rel, "_dot_", ".")
		src, err := templateFS.ReadFile(path)
		if err != nil {
			return err
		}
		t, err := template.New(rel).Delims("[[", "]]").Parse(string(src))
		if err != nil {
			return fmt.Errorf("template %s: %w", rel, err)
		}
		var out bytes.Buffer
		if err := t.Execute(&out, data); err != nil {
			return fmt.Errorf("template %s: %w", rel, err)
		}
		dst := filepath.Join(dir, filepath.FromSlash(rel))
		if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
			return err
		}
		return os.WriteFile(dst, out.Bytes(), 0o644)
	})
}

func title(name string) string {
	words := strings.Split(name, "-")
	for i, w := range words {
		if w != "" {
			r := []rune(w)
			r[0] = unicode.ToUpper(r[0])
			words[i] = string(r)
		}
	}
	return strings.Join(words, " ")
}