package main

import (
	"fmt"
	"io"
	"log"
	"log/slog"
	"mime"
	"net"
	"net/http"
	"os"
	"strings"
	"time"

	cfg "website/internal/config"

	"github.com/getsentry/sentry-go"
	sentryhttp "github.com/getsentry/sentry-go/http"
	"github.com/shengyanli1982/law"
)

var config *cfg.Config

type HTTPError struct {
	Error   error
	Message string
	Code    int
}

func canonicalisePath(path string) (cPath string, differs bool) {
	cPath = path
	if strings.HasSuffix(path, "/index.html") {
		cPath, differs = strings.CutSuffix(path, "index.html")
	} else if !strings.HasSuffix(path, "/") && files[path+"/"] != (File{}) {
		cPath, differs = path+"/", true
	}
	return cPath, differs
}

func serveFile(w http.ResponseWriter, r *http.Request) *HTTPError {
	urlPath, shouldRedirect := canonicalisePath(r.URL.Path)
	if shouldRedirect {
		http.Redirect(w, r, urlPath, 302)
		return nil
	}
	file := GetFile(urlPath)
	if file == (File{}) {
		return &HTTPError{
			Message: "File not found",
			Code:    http.StatusNotFound,
		}
	}
	w.Header().Add("ETag", file.etag)
	w.Header().Add("Vary", "Accept-Encoding")
	for k, v := range config.Extra.Headers {
		w.Header().Add(k, v)
	}

	http.ServeFile(w, r, files[urlPath].filename)
	return nil
}

type webHandler func(http.ResponseWriter, *http.Request) *HTTPError

func (fn webHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	defer func() {
		if fail := recover(); fail != nil {
			w.WriteHeader(http.StatusInternalServerError)
			slog.Error("runtime panic!", "error", fail)
		}
	}()
	w.Header().Set("Server", fmt.Sprintf("website (%s)", ShortSHA))
	if err := fn(w, r); err != nil {
		if strings.Contains(r.Header.Get("Accept"), "text/html") {
			w.WriteHeader(err.Code)
			notFoundPage := "website/private/404.html"
			http.ServeFile(w, r, notFoundPage)
		} else {
			http.Error(w, err.Message, err.Code)
		}
	}
}

var newMIMEs = map[string]string{
	".xsl": "text/xsl",
}

func fixupMIMETypes() {
	for ext, newType := range newMIMEs {
		if err := mime.AddExtensionType(ext, newType); err != nil {
			slog.Error("could not update mime type", "ext", ext, "mime", newType)
		}
	}
}

func startServer(runtimeConfig *Config) {
	fixupMIMETypes()

	c, err := cfg.GetConfig()
	if err != nil {
		log.Panicf("parsing configuration file: %v", err)
	}
	config = c

	prefix := "website/public"
	slog.Debug("registering content files", "prefix", prefix)
	err = registerContentFiles(prefix)
	if err != nil {
		log.Panicf("registering content files: %v", err)
	}

	env := "development"
	if runtimeConfig.Production {
		env = "production"
	}
	err = sentry.Init(sentry.ClientOptions{
		EnableTracing:    true,
		TracesSampleRate: 1.0,
		Dsn:              os.Getenv("SENTRY_DSN"),
		Release:          CommitSHA,
		Environment:      env,
	})
	if err != nil {
		log.Panic("could not set up sentry")
	}
	defer sentry.Flush(2 * time.Second)
	sentryHandler := sentryhttp.New(sentryhttp.Options{
		Repanic: true,
	})

	mux := http.NewServeMux()
	slog.Debug("binding main handler to", "host", runtimeConfig.BaseURL.Hostname()+"/")
	mux.Handle(runtimeConfig.BaseURL.Hostname()+"/", webHandler(serveFile))

	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		newURL := runtimeConfig.BaseURL.String() + r.URL.String()
		http.Redirect(w, r, newURL, 301)
	})

	var logWriter io.Writer
	if runtimeConfig.Production {
		logWriter = law.NewWriteAsyncer(os.Stdout, nil)
	} else {
		logWriter = os.Stdout
	}
	http.Handle("/",
		sentryHandler.Handle(
			wrapHandlerWithLogging(mux, wrappedHandlerOptions{
				defaultHostname: runtimeConfig.BaseURL.Hostname(),
				logger:          logWriter,
			}),
		),
	)
	// no logging, no sentry
	http.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
	})

	listenAddress := net.JoinHostPort(runtimeConfig.ListenAddress, fmt.Sprint(runtimeConfig.Port))
	log.Fatal(http.ListenAndServe(listenAddress, nil))
}