// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: PolyForm-Noncommercial-1.0.0

package admin

import (
	"fmt"
	"io"
	"net/http"
	"path/filepath"
	"strings"

	"sourcedock.dev/petrbalvin/volumen/internal/i18n"
	"sourcedock.dev/petrbalvin/volumen/internal/payloads"
	"sourcedock.dev/petrbalvin/volumen/internal/post"
)

func (a *Admin) handleImportForm(w http.ResponseWriter, r *http.Request) {
	data := a.pageData(r)
	data.Crumbs = []Crumb{
		{Label: "Posts", Href: "/admin/", UI: true},
		{Label: "Import", IsLast: true, UI: true},
	}
	a.renderPage(w, r, "import.html", data, http.StatusOK)
}

func (a *Admin) handleImport(w http.ResponseWriter, r *http.Request) {
	if !a.requireCSRF(w, r) {
		return
	}
	data := a.pageData(r)
	data.Crumbs = []Crumb{
		{Label: "Posts", Href: "/admin/", UI: true},
		{Label: "Import", IsLast: true, UI: true},
	}
	fail := func(msg string) {
		data.Error = i18n.Admin.T(data.Lang, msg)
		a.renderPage(w, r, "import.html", data, http.StatusUnprocessableEntity)
	}

	file, header, err := r.FormFile("file")
	if err != nil {
		fail("No file selected.")
		return
	}
	defer file.Close()
	if !strings.HasSuffix(strings.ToLower(header.Filename), ".md") {
		fail("Only .md files are accepted.")
		return
	}
	raw, err := readLimited(file, int64(a.deps.Config.Admin.MaxUploadBytes))
	if err != nil {
		fail("File is too large.")
		return
	}
	content := string(raw)
	p, err := post.Parse(content)
	if err != nil {
		fail(i18n.Admin.Tf(data.Lang, "The file could not be read as a post: %s", err.Error()))
		return
	}
	if p.Slug() == "" {
		base := strings.ToLower(filepath.Base(header.Filename))
		stem := strings.TrimSuffix(base, filepath.Ext(base))
		p.Metadata.Set("slug", strings.ReplaceAll(stem, " ", "-"))
	}
	if p.Lang() == "" {
		p.Metadata.Set("lang", a.deps.Config.Site.Language)
	}
	if err := payloads.CreationError(p, a.deps.Store, nil); err != nil {
		fail(err.Error())
		return
	}
	if _, err := a.deps.Store.Save(p); err != nil {
		fail("Import failed.")
		return
	}
	http.Redirect(w, r, "/admin/posts/"+p.Slug()+"/edit", http.StatusSeeOther)
}

// readLimited reads at most limit+1 bytes so callers can detect
// oversize uploads.
func readLimited(r io.Reader, limit int64) ([]byte, error) {
	raw, err := io.ReadAll(io.LimitReader(r, limit+1))
	if err != nil {
		return nil, err
	}
	if int64(len(raw)) > limit {
		return nil, fmt.Errorf("payload too large")
	}
	return raw, nil
}