package main

import (
	"context"
	"errors"
	"fmt"
	"io"
	"math/rand"
	"net/http"
	"net/http/httptest"
	"net/url"
	"os"
	"path"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"
	"unicode"

	"github.com/PuerkitoBio/goquery"
	"github.com/araddon/dateparse"
	"github.com/c2h5oh/datasize"
	tdl "github.com/mergestat/timediff/locale"
	"github.com/microcosm-cc/bluemonday"
	"github.com/samber/lo"
	"go.goblog.app/app/pkgs/bufferpool"
	"golang.org/x/text/language"
)

type contextKey string

func urlize(str string) string {
	return strings.Map(func(c rune) rune {
		if c >= 'a' && c <= 'z' || c >= '0' && c <= '9' {
			// Is lower case ASCII or number, return unmodified
			return c
		} else if c >= 'A' && c <= 'Z' {
			// Is upper case ASCII, make lower case
			return c + 'a' - 'A'
		} else if c == ' ' {
			// Space, replace with '-'
			return '-'
		} else {
			// Drop character
			return -1
		}
	}, str)
}

func sortedStrings(s []string) []string {
	sort.Slice(s, func(i, j int) bool {
		return strings.ToLower(s[i]) < strings.ToLower(s[j])
	})
	return s
}

var defaultLetters = []rune("abcdefghijklmnopqrstuvwxyz")

func randomString(n int, allowedChars ...[]rune) string {
	letters := append(allowedChars, defaultLetters)[0]
	b := make([]rune, n)
	for i := range b {
		b[i] = letters[rand.Intn(len(letters))]
	}
	return string(b)
}

func isAbsoluteURL(s string) bool {
	if u, err := url.Parse(s); err != nil || !u.IsAbs() {
		return false
	}
	return true
}

func allLinksFromHTMLString(html, baseURL string) ([]string, error) {
	return allLinksFromHTML(strings.NewReader(html), baseURL)
}

func allLinksFromHTML(r io.Reader, baseURL string) ([]string, error) {
	doc, err := goquery.NewDocumentFromReader(r)
	if err != nil {
		return nil, err
	}
	links := []string{}
	doc.Find("a[href]").Each(func(_ int, item *goquery.Selection) {
		if href, exists := item.Attr("href"); exists {
			links = append(links, href)
		}
	})
	links, err = resolveURLReferences(baseURL, links...)
	return lo.Uniq(links), err
}

func resolveURLReferences(base string, refs ...string) ([]string, error) {
	b, err := url.Parse(base)
	if err != nil {
		return nil, err
	}
	urls := make([]string, 0)
	for _, r := range refs {
		u, err := url.Parse(r)
		if err != nil {
			continue
		}
		urls = append(urls, b.ResolveReference(u).String())
	}
	return urls, nil
}

func unescapedPath(p string) string {
	if u, err := url.PathUnescape(p); err == nil {
		return u
	}
	return p
}

func lowerUnescapedPath(p string) string {
	return strings.ToLower(unescapedPath(p))
}

type stringGroup struct {
	Identifier string
	Strings    []string
}

func groupStrings(toGroup []string) []stringGroup {
	// Group strings and map them to stringGroups
	stringGroups := lo.MapToSlice(
		// strings -> map
		lo.GroupBy(toGroup, func(s string) string {
			return strings.ToUpper(string([]rune(s)[0]))
		}),
		// map -> stringGroups
		func(key string, strings []string) stringGroup {
			return stringGroup{
				Identifier: key,
				Strings:    sortedStrings(strings),
			}
		},
	)
	// Sort stringGroups
	sort.Slice(stringGroups, func(i, j int) bool {
		return strings.ToLower(stringGroups[i].Identifier) < strings.ToLower(stringGroups[j].Identifier)
	})
	return stringGroups
}

func toLocalSafe(s string) string {
	d, _ := toLocal(s)
	return d
}

func toLocal(s string) (string, error) {
	if s == "" {
		return "", nil
	}
	d, err := dateparse.ParseLocal(s)
	if err != nil {
		return "", err
	}
	return d.Local().Format(time.RFC3339), nil
}

func toUTCSafe(s string) string {
	d, _ := toUTC(s)
	return d
}

func toUTC(s string) (string, error) {
	if s == "" {
		return "", nil
	}
	d, err := dateparse.ParseLocal(s)
	if err != nil {
		return "", err
	}
	return d.UTC().Format(time.RFC3339), nil
}

func toLocalTime(date string) time.Time {
	if date == "" {
		return time.Time{}
	}
	d, err := dateparse.ParseLocal(date)
	if err != nil {
		return time.Time{}
	}
	return d.Local()
}

const isoDateFormat = "2006-01-02"

func utcNowString() string {
	return time.Now().UTC().Format(time.RFC3339)
}

func utcNowNanos() int64 {
	return time.Now().UTC().UnixNano()
}

type stringPair struct {
	First, Second string
}

func wordCount(s string) int {
	return len(strings.Fields(s))
}

// Count all letters and numbers in string
func charCount(s string) (count int) {
	for _, r := range s {
		if unicode.IsLetter(r) || unicode.IsNumber(r) {
			count++
		}
	}
	return count
}

// Check if url has allowed file extension
func urlHasExt(rawUrl string, allowed ...string) (ext string, has bool) {
	u, err := url.Parse(rawUrl)
	if err != nil {
		return "", false
	}
	ext = strings.ToLower(path.Ext(u.Path))
	if ext == "" {
		return "", false
	}
	ext = ext[1:]
	allowed = lo.Map(allowed, func(t string, _ int) string { return strings.ToLower(t) })
	return ext, lo.Contains(allowed, strings.ToLower(ext))
}

func mBytesString(size int64) string {
	return fmt.Sprintf("%.2f MB", datasize.ByteSize(size).MBytes())
}

func htmlText(s string) string {
	text, _ := htmlTextFromReader(strings.NewReader(s))
	return text
}

func htmlTextFromReader(r io.Reader) (string, error) {
	// Build policy to only allow a subset of HTML tags
	textPolicy := bluemonday.StrictPolicy()
	textPolicy.AllowElements("h1", "h2", "h3", "h4", "h5", "h6") // Headers
	textPolicy.AllowElements("p")                                // Paragraphs
	textPolicy.AllowElements("ol", "ul", "li")                   // Lists
	textPolicy.AllowElements("blockquote")                       // Blockquotes
	// Read filtered HTML into document
	doc, err := goquery.NewDocumentFromReader(textPolicy.SanitizeReader(r))
	if err != nil {
		return "", err
	}
	text := bufferpool.Get()
	defer bufferpool.Put(text)
	if bodyChild := doc.Find("body").Children(); bodyChild.Length() > 0 {
		// Input was real HTML, so build the text from the body
		// Declare recursive function to print childs
		var printChilds func(childs *goquery.Selection)
		printChilds = func(childs *goquery.Selection) {
			childs.Each(func(i int, sel *goquery.Selection) {
				if i > 0 && // Not first child
					sel.Is("h1, h2, h3, h4, h5, h6, p, ol, ul, li, blockquote") { // All elements that start a new paragraph
					_, _ = text.WriteString("\n\n")
				}
				if sel.Is("ol > li") { // List item in ordered list
					_, _ = fmt.Fprintf(text, "%d. ", i+1) // Add list item number
				}
				if sel.Children().Length() > 0 { // Has children
					printChilds(sel.Children()) // Recursive call to print childs
				} else {
					_, _ = text.WriteString(sel.Text()) // Print text
				}
			})
		}
		printChilds(bodyChild)
	} else {
		// Input was probably just text, so just use the text
		_, _ = text.WriteString(doc.Text())
	}
	// Trim whitespace and return
	return strings.TrimSpace(text.String()), nil
}

func cleanHTMLText(s string) string {
	// Clean HTML with UGC policy and return text
	pr, pw := io.Pipe()
	go func() { _ = pw.CloseWithError(bluemonday.UGCPolicy().SanitizeReaderToWriter(strings.NewReader(s), pw)) }()
	var err error
	s, err = htmlTextFromReader(pr)
	_ = pr.CloseWithError(err)
	return s
}

func defaultIfEmpty(s, d string) string {
	if s == "" {
		return d
	}
	return s
}

func containsStrings(s string, subStrings ...string) bool {
	for _, ss := range subStrings {
		if strings.Contains(s, ss) {
			return true
		}
	}
	return false
}

func timeNoErr(t time.Time, _ error) time.Time {
	return t
}

type handlerRoundTripper struct {
	http.RoundTripper
	handler http.Handler
}

func (rt *handlerRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
	if rt.handler != nil {
		// Fake request with handler
		rec := httptest.NewRecorder()
		rt.handler.ServeHTTP(rec, req)
		resp := rec.Result()
		// Copy request to response
		resp.Request = req
		return resp, nil
	}
	return nil, errors.New("no handler")
}

func newHandlerClient(handler http.Handler) *http.Client {
	return &http.Client{Transport: &handlerRoundTripper{handler: handler}}
}

func doHandlerRequest(req *http.Request, handler http.Handler) (*http.Response, error) {
	if req.URL.Path == "" {
		req.URL.Path = "/"
	}
	return newHandlerClient(handler).Do(req)
}

func saveToFile(reader io.Reader, fileName string) error {
	// Create folder path if not exists
	if err := os.MkdirAll(filepath.Dir(fileName), os.ModePerm); err != nil {
		return err
	}
	// Create file
	out, err := os.Create(fileName)
	if err != nil {
		return err
	}
	// Copy response to file
	defer out.Close()
	_, err = io.Copy(out, reader)
	return err
}

//nolint:containedctx
type valueOnlyContext struct {
	context.Context
}

func (valueOnlyContext) Deadline() (deadline time.Time, ok bool) {
	return
}

func (valueOnlyContext) Done() <-chan struct{} {
	return nil
}

func (valueOnlyContext) Err() error {
	return nil
}

var timeDiffLocaleMap = map[string]tdl.Locale{}
var timeDiffLocaleMutex sync.RWMutex

func matchTimeDiffLocale(lang string) tdl.Locale {
	timeDiffLocaleMutex.RLock()
	if locale, ok := timeDiffLocaleMap[lang]; ok {
		return locale
	}
	timeDiffLocaleMutex.RUnlock()
	timeDiffLocaleMutex.Lock()
	defer timeDiffLocaleMutex.Unlock()
	supportedLangs := []string{"en", "de", "es", "hi", "pt", "ru", "zh-CN"}
	supportedTags := []language.Tag{}
	for _, lang := range supportedLangs {
		supportedTags = append(supportedTags, language.Make(lang))
	}
	matcher := language.NewMatcher(supportedTags)
	_, idx, _ := matcher.Match(language.Make(lang))
	locale := tdl.Locale(supportedLangs[idx])
	timeDiffLocaleMap[lang] = locale
	return locale
}

func stringToInt(s string) int {
	i, _ := strconv.Atoi(s)
	return i
}

func loStringNotEmpty(s string, _ int) bool {
	return s != ""
}

func truncateStringWithEllipsis(s string, l int) string {
	if tr := []rune(s); len(tr) > l && l > 3 {
		return string(tr[0:l-3]) + "…"
	}
	return s
}