package frontend

import (
	"embed"
	"fmt"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"strings"
	"time"

	"git.noctra.dev/noctra/servtex/backend"
	"git.noctra.dev/noctra/servtex/globals"
)

//go:embed jscss/bootstrap.min.css
//go:embed jscss/custom-view.css
//go:embed jscss/htmx.min.js
//go:embed jscss/htmx-ext-sse.js
//go:embed templates/main.html
var WebFiles embed.FS

// Sends a Ping to keep the connection alive
func ssePing(writer *http.ResponseWriter) {
	fmt.Fprintf((*writer), ": ping\n\n")

	(*writer).(http.Flusher).Flush()
}

// Sends new Event
//
// Reads globals.LatexExec
func sseStatusSend(writer *http.ResponseWriter) {
	fmt.Fprintf((*writer), "event: status\n")
	fmt.Fprintf((*writer), "data: Execution Time:  %s<br>\n", globals.LatexExec.Timestamp)
	fmt.Fprintf((*writer), "data: Execution State: %s<br>\n\n", globals.LatexExec.ExecutionState)

	(*writer).(http.Flusher).Flush()
	backend.LogLine("Status Event has been sent", 1)
}

// Sends new Event
//
// Reads globals.LatexExec
func ssePDFSend(writer *http.ResponseWriter) {
	fmt.Fprintf((*writer), "event: pdf\n")
	iframe := fmt.Sprintf(
		`<iframe class="pdf-frame" src="/pdf?ts=%s"></iframe>`, 
		url.QueryEscape(backend.GetLocalTimeRFC()),
	)
	fmt.Fprintf((*writer), "data: %s\n\n", iframe)

	(*writer).(http.Flusher).Flush()
	backend.LogLine("PDF Event has been sent", 1)
}

// Sends new Event
//
// Reads globals.LatexExec
func sseOutputSend(writer *http.ResponseWriter) {
	fmt.Fprintf((*writer), "event: output\n")
	lines := strings.SplitSeq(string(globals.LatexExec.Output), "\n")
	for line := range lines {
		fmt.Fprintf((*writer), "data: %s<br>\n", line)
	}
	fmt.Fprintf((*writer), "\n")

	(*writer).(http.Flusher).Flush()
	backend.LogLine("Output Event has been sent", 1)
}

// Server Side Event Handler
//
// Sends a Ping instead of actual data when no new data available to save bandwidth
func SSEventHandler(writer http.ResponseWriter, request *http.Request) {
	writer.Header().Set("Content-Type", "text/event-stream")
	writer.Header().Set("Cache-Control", "no-cache")
	writer.Header().Set("Connection", "keep-alive")
	lastExecution := "startup"
	for range time.Tick(time.Second) {
		if lastExecution == globals.LatexExec.Timestamp {
			ssePing(&writer)
		} else {
			sseStatusSend(&writer)
			ssePDFSend(&writer)
			sseOutputSend(&writer)
			// comment out for testing purposes
			lastExecution = globals.LatexExec.Timestamp
		}
	}
}

// Serves the compiled PDF file
func PDFHandler(writer http.ResponseWriter, request *http.Request) {
	pdfPath := filepath.Join(globals.AppConfig.LatexOutputPath, "servtex.pdf")
	pdf, err := os.Open(pdfPath)
	if err != nil {
		backend.LogLine("PDF file could not be found or read", 1)
		http.NotFound(writer, request)
		return
	}
	defer pdf.Close()

	writer.Header().Set("Content-Type", "application/pdf")
	http.ServeFile(writer, request, pdfPath)
}

// Serves the main page of ServTeX
func MainHandler(writer http.ResponseWriter, request *http.Request) {
	writer.Header().Set("Content-Type", "text/html")
	main, _ := WebFiles.ReadFile("templates/main.html")
	writer.Write(main)
}

func PDFCompile(writer http.ResponseWriter, request *http.Request) {
	backend.LatexCompile(globals.AppConfig, &globals.LatexExec)
}