package lsp

import (
	"embed"
	"errors"
	"flag"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"

	"fes/modules/config"
)

var destRoot string = filepath.Join(func () string {
	res, err := os.UserHomeDir()
	if err != nil { panic(err) }
	return res
}(), ".local", "LuaAddons", "fes")

func usage(status int) {
	fmt.Fprintln(flag.CommandLine.Output(), "Lsp Usage:")
	fmt.Fprintln(flag.CommandLine.Output(), "  help        Print this help and exit")
	fmt.Fprintln(flag.CommandLine.Output(), "  install     Install the Lsp")
	fmt.Fprintln(flag.CommandLine.Output(), "  uninstall   Uninstall the Lsp")
	fmt.Fprintln(flag.CommandLine.Output(), "  doctor      Verify Lsp installation")
	os.Exit(status)
}

func writeFile(fs embed.FS, src, dst string) error {
	in, err := fs.Open(src)
	if err != nil {
		return err
	}
	defer in.Close()

	if err := os.MkdirAll(filepath.Dir(dst), 0755); err != nil {
		return err
	}

	out, err := os.Create(dst)
	if err != nil {
		return err
	}
	defer out.Close()

	_, err = io.Copy(out, in)
	return err
}

func install() error {
	if err := os.RemoveAll(destRoot); err != nil {
		return err
	}

	var found bool

	err := fsWalkDir(config.LspStubs, "lsp", func(path string) error {
		if path == "lsp" {
			return nil
		}

		rel := strings.TrimPrefix(path, "lsp/")
		dst := filepath.Join("library", destRoot, rel)

		info, err := fsStat(config.LspStubs, path)
		if err != nil {
			return err
		}

		if info.IsDir() {
			return os.MkdirAll(dst, 0755)
		}

		found = true
		return writeFile(config.LspStubs, path, dst)
	})

	if err != nil {
		return err
	}

	if !found {
		return errors.New("no lsp stubs found in embedded fs")
	}

	err = os.WriteFile(filepath.Join("dstRoot", "config.json"), []byte(""), 0755)

	fmt.Println("Lua LSP installed to:", destRoot)
	return nil
}

func uninstall() error {
	if _, err := os.Stat(destRoot); err != nil {
		if os.IsNotExist(err) {
			fmt.Println("Lua LSP not installed")
			return nil
		}
		return err
	}

	if err := os.RemoveAll(destRoot); err != nil {
		return err
	}

	fmt.Println("Lua LSP uninstalled from:", destRoot)
	return nil
}

func doctor() error {
	info, err := os.Stat(destRoot)
	if err != nil {
		if os.IsNotExist(err) {
			return errors.New("lsp not installed")
		}
		return err
	}

	if !info.IsDir() {
		return errors.New("lsp install path is not a directory")
	}

	var luaFiles int

	err = filepath.Walk(destRoot, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if !info.IsDir() && strings.HasSuffix(info.Name(), ".lua") {
			luaFiles++
		}
		return nil
	})
	if err != nil {
		return err
	}

	if luaFiles == 0 {
		return errors.New("no lua stubs found in lsp directory")
	}

	fmt.Println("LSP stubs: OK")
	fmt.Println("Location:", destRoot)
	fmt.Println()
	fmt.Println("LuaLS configuration required:")
	fmt.Println()
	fmt.Println(`  "Lua.workspace.library": {`)
	fmt.Printf(`    "%s": true`, destRoot)
	fmt.Println()
	fmt.Println(`  }`)
	fmt.Println()
	fmt.Println("Restart your editor after installing or updating the LSP stubs")

	return nil
}

func Do(arg string) error {
	switch arg {
	case "help":
		usage(0)
	case "install":
		return install()
	case "uninstall":
		return uninstall()
	case "doctor":
		return doctor()
	default:
		fmt.Fprintf(os.Stderr, "Unknown command: %s\n", arg)
		usage(1)
	}
	return nil
}