package commands

import (
	"bufio"
	"fmt"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"time"

	"embed"

	"github.com/facundoolano/jorge/config"
	"github.com/facundoolano/jorge/site"
	"golang.org/x/text/unicode/norm"
)

//go:embed all:initfiles
var initfiles embed.FS

var INIT_CONFIG string = `name: "%s"
author: "%s"
url: "%s"
`
var INIT_README string = `
# %s

A jorge blog by %s.
`
var DEFAULT_FRONTMATTER string = `---
title: %s
date: %s
layout: post
lang: %s
tags: []
---
`

var DEFAULT_ORG_DIRECTIVES string = `#+OPTIONS: toc:nil num:nil
#+LANGUAGE: %s
`

const FILE_RW_MODE = 0777

// Initialize a new jorge project in the given directory,
// prompting for basic site config and creating default files.
func Init(projectDir string) error {
	if err := ensureEmptyProjectDir(projectDir); err != nil {
		return err
	}

	siteName := Prompt("site name")
	siteUrl := Prompt("site url")
	siteAuthor := Prompt("author")

	// creating config and readme files manually, since I want to use the supplied config values in their
	// contents. (I don't want to render liquid templates in the WalkDir below since some of the initfiles
	// are actual templates that should be left as is).
	configFile := fmt.Sprintf(INIT_CONFIG, siteName, siteAuthor, siteUrl)
	readmeFile := fmt.Sprintf(INIT_README, siteName, siteAuthor)
	os.WriteFile(filepath.Join(projectDir, "config.yml"), []byte(configFile), site.FILE_RW_MODE)
	os.WriteFile(filepath.Join(projectDir, "README.md"), []byte(readmeFile), site.FILE_RW_MODE)

	// walk over initfiles fs
	// copy create directories and copy files at target

	initfilesRoot := "initfiles"
	return fs.WalkDir(initfiles, initfilesRoot, func(path string, entry fs.DirEntry, err error) error {
		if path == initfilesRoot {
			return nil
		}
		subpath, _ := filepath.Rel(initfilesRoot, path)
		targetPath := filepath.Join(projectDir, subpath)

		// if it's a directory create it at the same location
		if entry.IsDir() {
			return os.MkdirAll(targetPath, FILE_RW_MODE)
		}

		// TODO duplicated in site, extract to somewhere else
		// if its a file, copy it over
		targetFile, err := os.Create(targetPath)
		if err != nil {
			return err
		}
		defer targetFile.Close()

		source, err := initfiles.Open(path)
		if err != nil {
			return err
		}
		defer source.Close()

		_, err = io.Copy(targetFile, source)
		if err != nil {
			return err
		}
		fmt.Println("added", path)
		return targetFile.Sync()
	})
}

// Create a new post template in the given site, with the given title,
// with pre-filled front matter.
func Post(root string, title string) error {
	config, err := config.Load(root)
	if err != nil {
		return err
	}

	now := time.Now()
	slug := slugify(title)
	filename := strings.ReplaceAll(config.PostFormat, ":title", slug)
	filename = strings.ReplaceAll(filename, ":year", fmt.Sprint(now.Year()))
	filename = strings.ReplaceAll(filename, ":month", fmt.Sprint(int(now.Month())))
	filename = strings.ReplaceAll(filename, ":day", fmt.Sprint(now.Day()))
	path := filepath.Join(config.SrcDir, filename)

	// ensure the dir already exists
	if err := os.MkdirAll(filepath.Dir(path), FILE_RW_MODE); err != nil {
		return err
	}

	// if file already exists, prompt user for a different one
	if _, err := os.Stat(path); os.IsExist(err) {
		fmt.Printf("%s already exists\n", path)
		filename = Prompt("filename")
		path = filepath.Join(config.SrcDir, filename)
	}

	// initialize the post front matter
	content := fmt.Sprintf(DEFAULT_FRONTMATTER, title, now.Format(time.DateTime), config.Lang)

	// org files need some extra boilerplate
	if filepath.Ext(path) == ".org" {
		content += fmt.Sprintf(DEFAULT_ORG_DIRECTIVES, config.Lang)
	}

	if err := os.WriteFile(path, []byte(content), FILE_RW_MODE); err != nil {
		return err
	}
	fmt.Println("added", path)
	return nil
}

// Read the files in src/ render them and copy the result to target/
func Build(root string) error {
	config, err := config.Load(root)
	if err != nil {
		return err
	}

	site, err := site.Load(*config)
	if err != nil {
		return err
	}

	return site.Build()
}

// Prompt the user for a string value
func Prompt(label string) string {
	// https://dev.to/tidalcloud/interactive-cli-prompts-in-go-3bj9
	var s string
	r := bufio.NewReader(os.Stdin)
	for {
		fmt.Fprint(os.Stderr, label+": ")
		s, _ = r.ReadString('\n')
		if s != "" {
			break
		}
	}
	return strings.TrimSpace(s)
}

func ensureEmptyProjectDir(projectDir string) error {
	if err := os.Mkdir(projectDir, 0777); err != nil {
		// if it fails with dir already exist, check if it's empty
		// https://stackoverflow.com/a/30708914/993769
		if os.IsExist(err) {
			// check if empty
			dir, err := os.Open(projectDir)
			if err != nil {
				return err
			}
			defer dir.Close()

			// if directory is non empty, fail
			_, err = dir.Readdirnames(1)
			if err == nil {
				return fmt.Errorf("non empty directory %s", projectDir)
			}
			return err
		}
	}
	return nil
}

var nonWordRegex = regexp.MustCompile(`[^\w-]`)
var whitespaceRegex = regexp.MustCompile(`\s+`)

func slugify(title string) string {
	slug := strings.ToLower(title)
	slug = strings.TrimSpace(slug)
	slug = norm.NFD.String(slug)
	slug = whitespaceRegex.ReplaceAllString(slug, "-")
	slug = nonWordRegex.ReplaceAllString(slug, "")

	return slug
}