package app

import (
	"bytes"
	"encoding/json"
	"maxwarden/entries"
	"maxwarden/middleware"
	"maxwarden/query"
	"maxwarden/security"
	. "maxwarden/ui"
	"maxwarden/users"
	"net/http"
	"time"

	. "maragu.dev/gomponents"
	. "maragu.dev/gomponents/html"
)

func ExportBitwardenHandler(w http.ResponseWriter, r *http.Request) {
	identity := middleware.GetIdentity(r)
	session := middleware.GetSession(r)

	renderView := func(errorMessage string) {
		AppLayout("Export Vault", *identity, session,
			Card(
				Heading("Bitwarden export"),
				P(Text("Download your MaxWarden vault in one of Bitwarden's native import formats.")),
				P(
					InlineStyle("$me { margin-top: $3; }"),
					Text("In Bitwarden, choose the File format that exactly matches the download: Bitwarden (csv) or Bitwarden (json). CSV is recommended if Bitwarden reports a generic JSON import error."),
				),
				P(
					InlineStyle("$me { margin-top: $3; color: $color(red-700); font-weight: var(--font-weight-semibold); }"),
					Text("Warning: the downloaded file contains all usernames and passwords in plaintext. Store it securely and delete it when you are finished."),
				),
				If(errorMessage != "",
					P(
						InlineStyle("$me { margin-top: $3; color: $color(red-700); }"),
						Text(errorMessage),
					),
				),
				Form(
					InlineStyle("$me { margin-top: $5; }"),
					Action("/app/export/bitwarden"),
					Method(http.MethodPost),
					FormLabel(Text("Confirm your master key")),
					FormInput(
						Type("password"),
						Name("password"),
						AutoComplete("current-password"),
						Required(),
					),
					Br(),
					Div(
						InlineStyle("$me { display: flex; flex-wrap: wrap; gap: $3; margin-top: $3; }"),
						ButtonUIDanger(Type("submit"), Name("format"), Value("csv"), Text("Download Bitwarden CSV (recommended)")),
						ButtonUIOutline(Type("submit"), Name("format"), Value("json"), Text("Download Bitwarden JSON")),
					),
				),
			),
		).Render(w)
	}

	switch r.Method {
	case http.MethodGet:
		renderView("")
		return
	case http.MethodPost:
		// Continue below.
	default:
		w.Header().Set("Allow", http.MethodGet+", "+http.MethodPost)
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
	if err := r.ParseForm(); err != nil {
		http.Error(w, "Invalid export request", http.StatusBadRequest)
		return
	}

	user, err := users.FetchById(identity.UserID)
	if err != nil {
		http.Error(w, "Unable to verify account", http.StatusInternalServerError)
		return
	}

	if !security.ComparePasswords(r.Form.Get("password"), user.Password) {
		w.WriteHeader(http.StatusUnauthorized)
		renderView("The master key is incorrect.")
		return
	}

	secretList, err := entries.Filter(entries.EntryFilter{
		Filter:    query.NewFilterFromSearch(map[string]string{}),
		UserId:    identity.UserID,
		MasterKey: identity.MasterKey,
	})
	if err != nil {
		http.Error(w, "Unable to decrypt vault", http.StatusInternalServerError)
		return
	}

	format := r.Form.Get("format")
	var document []byte
	var extension string
	var contentType string

	switch format {
	case "", "csv":
		var csvDocument bytes.Buffer
		if err := entries.WriteBitwardenCSV(&csvDocument, secretList); err != nil {
			http.Error(w, "Unable to create export", http.StatusInternalServerError)
			return
		}
		document = csvDocument.Bytes()
		extension = "csv"
		contentType = "text/csv; charset=utf-8"
	case "json":
		document, err = json.MarshalIndent(entries.NewBitwardenExport(secretList), "", "  ")
		if err != nil {
			http.Error(w, "Unable to create export", http.StatusInternalServerError)
			return
		}
		extension = "json"
		contentType = "application/json; charset=utf-8"
	default:
		http.Error(w, "Unsupported export format", http.StatusBadRequest)
		return
	}

	filename := "maxwarden-bitwarden-export-" + time.Now().UTC().Format("2006-01-02") + "." + extension
	w.Header().Set("Cache-Control", "no-store")
	w.Header().Set("Content-Disposition", `attachment; filename="`+filename+`"`)
	w.Header().Set("Content-Type", contentType)
	w.Header().Set("Pragma", "no-cache")
	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.Write(document)
}