package common

import (
	"bytes"
	"compress/gzip"
	"crypto/sha256"
	"encoding/hex"
	"errors"
	"fmt"
	"io/ioutil"
	"mime"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"sync"

	"github.com/Azareal/Gosora/tmpl_client"
)

type SFileList map[string]SFile

var StaticFiles SFileList = make(map[string]SFile)
var staticFileMutex sync.RWMutex

type SFile struct {
	Data             []byte
	GzipData         []byte
	Sha256           []byte
	Pos              int64
	Length           int64
	GzipLength       int64
	Mimetype         string
	Info             os.FileInfo
	FormattedModTime string
}

type CSSData struct {
	Phrases map[string]string
}

func (list SFileList) JSTmplInit() error {
	DebugLog("Initialising the client side templates")
	return filepath.Walk("./tmpl_client", func(path string, f os.FileInfo, err error) error {
		if f.IsDir() || strings.HasSuffix(path, "template_list.go") || strings.HasSuffix(path, "stub.go") {
			return nil
		}
		path = strings.Replace(path, "\\", "/", -1)
		DebugLog("Processing client template " + path)
		data, err := ioutil.ReadFile(path)
		if err != nil {
			return err
		}

		path = strings.TrimPrefix(path, "tmpl_client/")
		tmplName := strings.TrimSuffix(path, ".go")
		shortName := strings.TrimPrefix(tmplName, "template_")

		var replace = func(data []byte, replaceThis string, withThis string) []byte {
			return bytes.Replace(data, []byte(replaceThis), []byte(withThis), -1)
		}

		startIndex, hasFunc := skipAllUntilCharsExist(data, 0, []byte("func init() {"))
		if !hasFunc {
			return errors.New("no init function found")
		}
		data = data[startIndex-len([]byte("func init() {")):]
		data = replace(data, "func ", "function ")
		data = replace(data, "function init() {", "if(tmplInits===undefined) var tmplInits = {};\ntmplInits[\""+tmplName+"\"] = ")
		data = replace(data, " error {\n", " {\nlet out = \"\"\n")
		funcIndex, hasFunc := skipAllUntilCharsExist(data, 0, []byte("function Template_"))
		if !hasFunc {
			return errors.New("no template function found")
		}
		spaceIndex, hasSpace := skipUntilIfExists(data, funcIndex, ' ')
		if !hasSpace {
			return errors.New("no spaces found after the template function name")
		}
		endBrace, hasBrace := skipUntilIfExists(data, spaceIndex, ')')
		if !hasBrace {
			return errors.New("no right brace found after the template function name")
		}
		fmt.Println("spaceIndex: ", spaceIndex)
		fmt.Println("endBrace: ", endBrace)
		fmt.Println("string(data[spaceIndex:endBrace]): ", string(data[spaceIndex:endBrace]))

		preLen := len(data)
		data = replace(data, string(data[spaceIndex:endBrace]), "")
		data = replace(data, "))\n", "  \n")
		endBrace -= preLen - len(data) // Offset it as we've deleted portions
		fmt.Println("new endBrace: ", endBrace)
		fmt.Println("data: ", string(data))

		/*var showPos = func(data []byte, index int) (out string) {
			out = "["
			for j, char := range data {
				if index == j {
					out += "[" + string(char) + "] "
				} else {
					out += string(char) + " "
				}
			}
			return out + "]"
		}*/
		data = replace(data, `)
	if !ok {
		return errors.New("invalid page struct value")
	}`, "*/tmpl_"+shortName+"_vars = tmpl_"+shortName+"_i")

		// ? Can we just use a regex? I'm thinking of going more efficient, or just outright rolling wasm, this is a temp hack in a place where performance doesn't particularly matter
		var each = func(phrase string, handle func(index int)) {
			//fmt.Println("find each '" + phrase + "'")
			var index = endBrace
			if index < 0 {
				panic("index under zero: " + strconv.Itoa(index))
			}
			var foundIt bool
			for {
				//fmt.Println("in index: ", index)
				//fmt.Println("pos: ", showPos(data, index))
				index, foundIt = skipAllUntilCharsExist(data, index, []byte(phrase))
				if !foundIt {
					break
				}
				handle(index)
			}
		}
		each("strconv.Itoa(", func(index int) {
			braceAt, hasEndBrace := skipUntilIfExistsOrLine(data, index, ')')
			if hasEndBrace {
				data[braceAt] = ' ' // Blank it
			}
		})
		each("[]byte(", func(index int) {
			braceAt, hasEndBrace := skipUntilIfExistsOrLine(data, index, ')')
			if hasEndBrace {
				data[braceAt] = ' ' // Blank it
			}
		})
		each("StringToBytes(", func(index int) {
			braceAt, hasEndBrace := skipUntilIfExistsOrLine(data, index, ')')
			if hasEndBrace {
				data[braceAt] = ' ' // Blank it
			}
		})
		each("w.Write(", func(index int) {
			braceAt, hasEndBrace := skipUntilIfExistsOrLine(data, index, ')')
			if hasEndBrace {
				data[braceAt] = ' ' // Blank it
			}
		})
		each("RelativeTime(", func(index int) {
			braceAt, _ := skipUntilIfExistsOrLine(data, index, 10)
			if data[braceAt-1] == ' ' {
				data[braceAt-1] = ' ' // Blank it
			}
		})
		each("if ", func(index int) {
			//fmt.Println("if index: ", index)
			braceAt, hasBrace := skipUntilIfExistsOrLine(data, index, '{')
			if hasBrace {
				if data[braceAt-1] != ' ' {
					panic("couldn't find space before brace, found ' " + string(data[braceAt-1]) + "' instead")
				}
				data[braceAt-1] = ')' // Drop a brace here to satisfy JS
			}
		})
		each("for _, item := range ", func(index int) {
			//fmt.Println("for index: ", index)
			braceAt, hasBrace := skipUntilIfExists(data, index, '{')
			if hasBrace {
				if data[braceAt-1] != ' ' {
					panic("couldn't find space before brace, found ' " + string(data[braceAt-1]) + "' instead")
				}
				data[braceAt-1] = ')' // Drop a brace here to satisfy JS
			}
		})
		data = replace(data, "for _, item := range ", "for(item of ")
		data = replace(data, "w.Write([]byte(", "out += ")
		data = replace(data, "w.Write(StringToBytes(", "out += ")
		data = replace(data, "w.Write(", "out += ")
		data = replace(data, "strconv.Itoa(", "")
		data = replace(data, "strconv.FormatInt(", "")
		data = replace(data, "common.", "")
		data = replace(data, "phrases.", "")
		data = replace(data, ", 10;", "")
		data = replace(data, shortName+"_tmpl_phrase_id = RegisterTmplPhraseNames([]string{", "[")
		data = replace(data, "var plist = GetTmplPhrasesBytes("+shortName+"_tmpl_phrase_id)", "let plist = tmplPhrases[\""+tmplName+"\"];")
		data = replace(data, "var cached_var_", "let cached_var_")
		data = replace(data, `tmpl_`+shortName+`_vars, ok := tmpl_`+shortName+`_i.`, `/*`)
		data = replace(data, "[]byte(", "")
		data = replace(data, "StringToBytes(", "")
		data = replace(data, "RelativeTime(tmpl_"+shortName+"_vars.", "tmpl_"+shortName+"_vars.Relative")
		// TODO: Format dates properly on the client side
		data = replace(data, ".Format(\"2006-01-02 15:04:05\"", "")
		data = replace(data, ", 10", "")
		data = replace(data, "if ", "if(")
		data = replace(data, "return nil", "return out")
		data = replace(data, " )", ")")
		data = replace(data, " \n", "\n")
		data = replace(data, "\n", ";\n")
		data = replace(data, "{;", "{")
		data = replace(data, "};", "}")
		data = replace(data, "[;", "[")
		data = replace(data, ";;", ";")
		data = replace(data, ",;", ",")
		data = replace(data, "=;", "=")
		data = replace(data, `,
	});
}`, "\n\t];")
		data = replace(data, `=
}`, "= []")

		fragset := tmpl.GetFrag(shortName)
		if fragset != nil {
			var sfrags = []byte("let " + shortName + "_frags = [];\n")
			for _, frags := range fragset {
				sfrags = append(sfrags, []byte(shortName+"_frags.push(`"+string(frags)+"`);\n")...)
			}
			data = append(sfrags, data...)
		}
		data = replace(data, "\n;", "\n")

		for name, _ := range Themes {
			if strings.HasSuffix(shortName, "_"+name) {
				data = append(data, "\nlet Template_"+strings.TrimSuffix(shortName, "_"+name)+" = Template_"+shortName+";"...)
				break
			}
		}

		path = tmplName + ".js"
		DebugLog("js path: ", path)
		var ext = filepath.Ext("/tmpl_client/" + path)
		gzipData, err := compressBytesGzip(data)
		if err != nil {
			return err
		}

		// Get a checksum for CSPs and cache busting
		hasher := sha256.New()
		hasher.Write(data)
		checksum := []byte(hex.EncodeToString(hasher.Sum(nil)))

		list.Set("/static/"+path, SFile{data, gzipData, checksum, 0, int64(len(data)), int64(len(gzipData)), mime.TypeByExtension(ext), f, f.ModTime().UTC().Format(http.TimeFormat)})

		DebugLogf("Added the '%s' static file.", path)
		return nil
	})
}

func (list SFileList) Init() error {
	return filepath.Walk("./public", func(path string, f os.FileInfo, err error) error {
		if f.IsDir() {
			return nil
		}

		path = strings.Replace(path, "\\", "/", -1)
		data, err := ioutil.ReadFile(path)
		if err != nil {
			return err
		}
		path = strings.TrimPrefix(path, "public/")
		var ext = filepath.Ext("/public/" + path)
		mimetype := mime.TypeByExtension(ext)

		// Get a checksum for CSPs and cache busting
		hasher := sha256.New()
		hasher.Write(data)
		checksum := []byte(hex.EncodeToString(hasher.Sum(nil)))

		// Avoid double-compressing images
		var gzipData []byte
		if mimetype != "image/jpeg" && mimetype != "image/png" && mimetype != "image/gif" {
			gzipData, err = compressBytesGzip(data)
			if err != nil {
				return err
			}
			// Don't use Gzip if we get meagre gains from it as it takes longer to process the responses
			if len(gzipData) >= (len(data) + 100) {
				gzipData = nil
			} else {
				diff := len(data) - len(gzipData)
				if diff <= len(data)/100 {
					gzipData = nil
				}
			}
		}

		list.Set("/static/"+path, SFile{data, gzipData, checksum, 0, int64(len(data)), int64(len(gzipData)), mimetype, f, f.ModTime().UTC().Format(http.TimeFormat)})

		DebugLogf("Added the '%s' static file.", path)
		return nil
	})
}

func (list SFileList) Add(path string, prefix string) error {
	data, err := ioutil.ReadFile(path)
	if err != nil {
		return err
	}
	fi, err := os.Open(path)
	if err != nil {
		return err
	}
	f, err := fi.Stat()
	if err != nil {
		return err
	}

	var ext = filepath.Ext(path)
	path = strings.TrimPrefix(path, prefix)
	gzipData, err := compressBytesGzip(data)
	if err != nil {
		return err
	}

	// Get a checksum for CSPs and cache busting
	hasher := sha256.New()
	hasher.Write(data)
	checksum := []byte(hex.EncodeToString(hasher.Sum(nil)))

	list.Set("/static"+path, SFile{data, gzipData, checksum, 0, int64(len(data)), int64(len(gzipData)), mime.TypeByExtension(ext), f, f.ModTime().UTC().Format(http.TimeFormat)})

	DebugLogf("Added the '%s' static file", path)
	return nil
}

func (list SFileList) Get(name string) (file SFile, exists bool) {
	staticFileMutex.RLock()
	defer staticFileMutex.RUnlock()
	file, exists = list[name]
	return file, exists
}

func (list SFileList) Set(name string, data SFile) {
	staticFileMutex.Lock()
	defer staticFileMutex.Unlock()
	list[name] = data
}

func compressBytesGzip(in []byte) ([]byte, error) {
	var buff bytes.Buffer
	gz, err := gzip.NewWriterLevel(&buff, gzip.BestCompression)
	if err != nil {
		return nil, err
	}
	_, err = gz.Write(in)
	if err != nil {
		return nil, err
	}
	err = gz.Close()
	if err != nil {
		return nil, err
	}
	return buff.Bytes(), nil
}