package routes

import (
	"bytes"
	"io"
	"log"
	"net/http"
	"strings"

	"github.com/alecthomas/chroma/v2/formatters/html"
	"github.com/alecthomas/chroma/v2/lexers"
	"github.com/alecthomas/chroma/v2/styles"
	"go.alanpearce.eu/elgit/git"
	"go.alanpearce.eu/elgit/templates"
)

func (d *deps) Write404(w http.ResponseWriter) {
	w.WriteHeader(http.StatusNotFound)
	data := templates.PageData{
		Meta: d.c.Meta,
	}
	if err := templates.NotFound(data).Render(w); err != nil {
		log.Printf("404 template: %s", err)
	}
}

func (d *deps) Write500(w http.ResponseWriter) {
	w.WriteHeader(http.StatusInternalServerError)
	data := templates.PageData{
		Meta: d.c.Meta,
	}
	if err := templates.ServerError(data).Render(w); err != nil {
		log.Printf("500 template: %s", err)
	}
}

func (d *deps) listFiles(files []git.NiceTree, data map[string]any, w http.ResponseWriter) {
	pageData := templates.PageData{
		Meta:        d.c.Meta,
		DisplayName: getDisplayName(data["name"].(string)),
		Name:        data["name"].(string),
		Ref:         data["ref"].(string),
		Description: data["desc"].(string),
		Parent:      "",
	}

	if parent, ok := data["parent"]; ok && parent != nil {
		pageData.Parent = parent.(string)
	}

	readme := ""
	if readmeContent, ok := data["readme"]; ok && readmeContent != nil {
		readme = readmeContent.(string)
	}

	dotdot := ""
	if dotdotPath, ok := data["dotdot"]; ok && dotdotPath != nil {
		dotdot = dotdotPath.(string)
	}

	if err := templates.Tree(pageData, files, readme, dotdot).Render(w); err != nil {
		log.Println(err)
		return
	}
}

func countLines(r io.Reader) (int, error) {
	buf := make([]byte, 32*1024)
	bufLen := 0
	count := 0
	nl := []byte{'\n'}

	for {
		c, err := r.Read(buf)
		if c > 0 {
			bufLen += c
		}
		count += bytes.Count(buf[:c], nl)

		switch {
		case err == io.EOF:
			/* handle last line not having a newline at the end */
			if bufLen >= 1 && buf[(bufLen-1)%(32*1024)] != '\n' {
				count++
			}
			return count, nil
		case err != nil:
			return 0, err
		}
	}
}

func (d *deps) showFileWithHighlight(
	name, content string,
	data map[string]any,
	w http.ResponseWriter,
) {
	lexer := lexers.Get(name)
	if lexer == nil {
		lexer = lexers.Get(".txt")
	}

	style := styles.Get(d.c.Meta.SyntaxHighlight)
	if style == nil {
		style = styles.Get("monokailight")
	}

	formatter := html.New(
		html.WithLineNumbers(true),
		html.WithLinkableLineNumbers(true, "L"),
	)

	iterator, err := lexer.Tokenise(nil, content)
	if err != nil {
		d.Write500(w)
		return
	}

	var code bytes.Buffer
	err = formatter.Format(&code, style, iterator)
	if err != nil {
		d.Write500(w)
		return
	}

	pageData := templates.PageData{
		Meta:        d.c.Meta,
		DisplayName: getDisplayName(data["name"].(string)),
		Content:     code.String(),
		Name:        data["name"].(string),
		Ref:         data["ref"].(string),
		Description: data["desc"].(string),
		Path:        data["path"].(string),
	}

	if err := templates.File(pageData, true).Render(w); err != nil {
		log.Println(err)
		return
	}
}

func (d *deps) showFile(content string, data map[string]any, w http.ResponseWriter) {
	lc, err := countLines(strings.NewReader(content))
	if err != nil {
		// Non-fatal, we'll just skip showing line numbers in the template.
		log.Printf("counting lines: %s", err)
	}

	lines := make([]int, lc)
	if lc > 0 {
		for i := range lines {
			lines[i] = i + 1
		}
	}

	pageData := templates.PageData{
		Meta:        d.c.Meta,
		DisplayName: getDisplayName(data["name"].(string)),
		LineCount:   lines,
		Content:     content,
		Name:        data["name"].(string),
		Ref:         data["ref"].(string),
		Description: data["desc"].(string),
		Path:        data["path"].(string),
	}

	if err := templates.File(pageData, false).Render(w); err != nil {
		log.Println(err)
		return
	}
}

func (d *deps) showRaw(content string, w http.ResponseWriter) {
	w.WriteHeader(http.StatusOK)
	w.Header().Set("Content-Type", "text/plain")
	_, err := w.Write([]byte(content))
	if err != nil {
		log.Println(err)
		d.Write500(w)
	}
}