// A website generator tool
package main

import (
	"tildegit.org/nihilazo/go-gemtext"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"io"
	"os"
	"path/filepath"
)

// TODO replace these hardcoded paths with config
var root string = "/mnt/term/home/nico/website/wiki"
var geminiPrefix string = "gemini://breadpunk.club/~bagel"
var htmlPrefix string = "https://itwont.work"
var geminiOutputDir string = filepath.Join(root, "public_gemini")
var htmlOutputDir string = filepath.Join(root, "public_html")
var inputDir string = filepath.Join(root, "content")
var tagFile string = filepath.Join(root, "tags.json")

type filePathInfo struct {
	Path string
	New  bool // True if the file is new
}

type pageInfo struct {
	Path  string
	Title string
}

// RemoveIndex is a reslicing function.
func RemoveIndex(s []pageInfo, index int) []pageInfo {
    return append(s[:index], s[index+1:]...)
}

var tagData map[string][]pageInfo = make(map[string][]pageInfo)

var files []filePathInfo // Files to process (those that are new or have been edited)

func copy(src, dst string) (int64, error) {
        sourceFileStat, err := os.Stat(src)
        if err != nil {
                return 0, err
        }

        if !sourceFileStat.Mode().IsRegular() {
                return 0, fmt.Errorf("%s is not a regular file", src)
        }

        source, err := os.Open(src)
        if err != nil {
                return 0, err
        }
        defer source.Close()

        destination, err := os.Create(dst)
        if err != nil {
                return 0, err
        }
        defer destination.Close()
        nBytes, err := io.Copy(destination, source)
        return nBytes, err
}

func processPage(f filePathInfo) error {

	// Delete any existing tag references to this file
	if filepath.Ext(f.Path) == ".gmi" {
		for i,d := range tagData { // For each tag in tagdata
			if len(d) != 0 {
				for j, _ := range d { // for each file in the tag
					if files[j].Path == f.Path {
						tagData[i] = RemoveIndex(d,j)
					}
				}
			}
		}
		// Open the file and parse the gemtext
		data, err := ioutil.ReadFile(f.Path)
		if err != nil {
			return err
		}
		parse, err := gemtext.ParsePage(string(data))
		if err != nil {
			return err
		}
		// TODO get tag data from files
		// TODO render and write HTML and gemini
	} else if filepath.Ext(f.Path) == ".tpl" {
		// TODO handle template files
	} else { // Non-gemtext files
		rel, err := filepath.Rel(inputDir, f.Path)
		if err != nil {
			return err
		}
		copy(f.Path, filepath.Join(htmlOutputDir, rel))
		copy(f.Path, filepath.Join(geminiOutputDir, rel))
	}
	
	return nil
}

// walkInputDir is called when walking the input directory, finds what files are new or have been edited, adds them to files
func walkInputDir(path string, info os.FileInfo, err error) error {
	if err != nil {
		return err
	}
	if !info.IsDir() {
		rel, err := filepath.Rel(inputDir, path)
		if err != nil {
			return err
		}
		outPath := filepath.Join(geminiOutputDir, rel)
		outFileInfo, err := os.Stat(outPath)
		if err != nil {
			if os.IsNotExist(err) {
				files = append(files, filePathInfo{Path: path, New: true})
			} else {
				return err
			}
		} else {
			if info.ModTime().After(outFileInfo.ModTime()) {
				files = append(files, filePathInfo{Path: path})
			}
		}

	}
	return nil
}
func main() {
	loadingJson := true
	if _, err := os.Stat(tagFile); err != nil {
		if os.IsNotExist(err) {
			loadingJson = false
			fmt.Println("Not loading tags file, it doesn't exist yet")
		} else {
			fmt.Println(err)
			return
		}
	}
	tagFileData, err := ioutil.ReadFile(tagFile)
	if loadingJson {
		err = json.Unmarshal([]byte(tagFileData), &tagData)
		if err != nil {
			fmt.Println(err)
			return
		}
	}
	err = filepath.Walk(inputDir, walkInputDir) // walks the tree, creates the files slice and updates tagData
	if err != nil {
		fmt.Println(err)
		return
	}
	for _, file := range files {
		err := processPage(file) // Process all the updated files.
		if err != nil {
			fmt.Println(err)
			return
		}
	}
	// TODO tag pages
	json, err := json.Marshal(tagData)
	err = ioutil.WriteFile(tagFile, json, 0644)
	if err != nil {
		fmt.Println(err)
		return
	}
}