package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

const defaultManifestURL = "https://drive.google.com/file/d/1lRmHIy_0nXEy_LTwn0NzIqoJ4s9_JmxO/view?usp=drive_link"

type ManifestEntry struct {
	Filename    string `json:"filename"`
	URL         string `json:"url"`
	Description string `json:"description,omitempty"`
}

var reGDriveFileID = regexp.MustCompile(`/file/d/([a-zA-Z0-9_-]+)`)
var reGDriveIDParam = regexp.MustCompile(`[?&]id=([a-zA-Z0-9_-]+)`)

func gdriveToDirectURL(rawURL string) string {
	if m := reGDriveFileID.FindStringSubmatch(rawURL); m != nil {
		return "https://drive.google.com/uc?export=download&id=" + m[1]
	}
	if m := reGDriveIDParam.FindStringSubmatch(rawURL); m != nil {
		return "https://drive.google.com/uc?export=download&id=" + m[1]
	}
	return rawURL
}

func fetchManifest(manifestURL string) ([]ManifestEntry, error) {
	req, err := http.NewRequest("GET", gdriveToDirectURL(manifestURL), nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("User-Agent", "Mozilla/5.0")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("HTTP %d %s", resp.StatusCode, resp.Status)
	}
	var entries []ManifestEntry
	if err := json.NewDecoder(resp.Body).Decode(&entries); err != nil {
		return nil, fmt.Errorf("failed to parse manifest JSON: %w", err)
	}
	filtered := entries[:0]
	for _, e := range entries {
		if e.Filename != "" && e.URL != "" {
			filtered = append(filtered, e)
		}
	}
	return filtered, nil
}

func downloadManifestFile(rawURL, destPath string) error {
	req, err := http.NewRequest("GET", gdriveToDirectURL(rawURL), nil)
	if err != nil {
		return err
	}
	req.Header.Set("User-Agent", "Mozilla/5.0")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("HTTP %d %s", resp.StatusCode, resp.Status)
	}
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	ct := resp.Header.Get("Content-Type")
	ext := strings.ToLower(filepath.Ext(destPath))
	if strings.Contains(ct, "text/html") && ext != ".html" && ext != ".htm" {
		return fmt.Errorf("got an HTML page instead of a file — make sure the Google Drive file is set to \"Anyone with the link can view\"")
	}
	return os.WriteFile(destPath, body, 0644)
}

func getManifestURL() string {
	cfg := LoadConfig()
	if cfg.ProjectInitManifestURL != "" {
		return cfg.ProjectInitManifestURL
	}
	return defaultManifestURL
}

func ProjectInitPage(w http.ResponseWriter, r *http.Request) {
	body := `
<header class="tool-header">
  <h2 class="tool-title">Initialize Project</h2>
  <p class="tool-description">Fetches the shared file list from your team manifest and downloads selected files into the chosen folder.</p>
</header>

<section class="tool-panel input-panel">
  <div class="panel-header" style="display:flex;align-items:center;justify-content:space-between;">
    <h3 class="panel-title">Files</h3>
    <div style="display:flex;gap:4px;align-items:center;">
      <span id="manifestSource" class="muted" style="font-size:11px;margin-right:4px;"></span>
      <button class="secondary" style="min-height:22px;width:26px;padding:0;font-size:14px;" title="Refresh manifest" onclick="refresh()">&#8635;</button>
      <button class="secondary" style="min-height:22px;width:26px;padding:0;font-size:14px;" title="Configure manifest URL" onclick="openSettingsModal('initialize-project')">&#9881;</button>
    </div>
  </div>
  <div class="panel-body">
    <div class="control-group">
      <div id="fileList"></div>
    </div>
    <div class="control-group">
      <p class="control-label">Download folder</p>
      <div class="field-row">
        <input type="text" id="destFolder" value="" placeholder="(no folder selected)" readonly style="flex:1;" />
        <button class="secondary" onclick="pickFolder()">Browse&#8230;</button>
      </div>
    </div>
    <div class="action-row">
      <button id="initBtn" onclick="initProject()" disabled>Initialize Project</button>
      <button id="selectAllBtn" class="secondary" onclick="toggleSelectAll()" style="display:none;">Deselect all</button>
    </div>
    <div id="status" class="status-panel"></div>
  </div>
</section>

<script>
  let files = [];
  let allSelected = true;

  function escapeHtml(s) {
    return String(s).replace(/[&<>"']/g, c => ({'&':'&amp;','<':'&lt;','>':'&gt;','"':'&quot;',"'":'&#39;'}[c]));
  }

  async function refresh() {
    setStatus('', '');
    document.getElementById('fileList').innerHTML = '<p class="muted" style="margin:0;">Loading manifest&#8230;</p>';
    document.getElementById('initBtn').disabled = true;
    document.getElementById('selectAllBtn').style.display = 'none';
    try {
      const r = await fetch('/api/project-init/manifest');
      const j = await r.json();
      if (j.error) { renderError(j.error); return; }
      renderFiles(j.files || [], j.manifestUrl || '');
    } catch (e) {
      renderError('Failed to load manifest: ' + (e.message || e));
    }
  }

  function renderError(msg) {
    document.getElementById('fileList').innerHTML = '<p class="err" style="margin:0;">' + escapeHtml(msg) + '</p>';
    document.getElementById('initBtn').disabled = true;
    document.getElementById('selectAllBtn').style.display = 'none';
    document.getElementById('manifestSource').textContent = '';
  }

  function renderFiles(list, manifestUrl) {
    files = list;
    allSelected = true;
    document.getElementById('manifestSource').textContent =
      manifestUrl ? '(' + manifestUrl.replace(/^https?:\/\//, '').split('/')[0] + ')' : '';

    if (!list.length) {
      document.getElementById('fileList').innerHTML = '<p class="muted" style="margin:0;">Manifest loaded but contains no files.</p>';
      document.getElementById('initBtn').disabled = true;
      document.getElementById('selectAllBtn').style.display = 'none';
      return;
    }

    const rows = list.map((f, i) =>
      '<tr>' +
        '<td style="width:20px;text-align:center;"><input type="checkbox" id="cb_' + i + '" checked /></td>' +
        '<td class="mono wrap" style="width:20%;">' + escapeHtml(f.filename) + '</td>' +
        '<td class="muted wrap" style="width:70%;">' + escapeHtml(f.description || '') + '</td>' +
        '<td style="width:10%;text-align:right;"><button style="min-height:22px;padding:2px 8px;font-size:11px;" onclick="openUrl(' + JSON.stringify(f.url) + ')">Open</button></td>' +
      '</tr>'
    ).join('');

    document.getElementById('fileList').innerHTML =
      '<div class="results-panel" style="margin-top:0;overflow-x:hidden;">' +
        '<table class="data-table">' +
          '<thead><tr><th style="width:20px;"></th><th style="width:20%;">Filename</th><th style="width:70%;">Description</th><th style="width:10%;"></th></tr></thead>' +
          '<tbody>' + rows + '</tbody>' +
        '</table>' +
      '</div>';

    document.getElementById('initBtn').disabled = false;
    document.getElementById('selectAllBtn').style.display = '';
    document.getElementById('selectAllBtn').textContent = 'Deselect all';
  }

  function toggleSelectAll() {
    allSelected = !allSelected;
    files.forEach((_, i) => { const cb = document.getElementById('cb_' + i); if (cb) cb.checked = allSelected; });
    document.getElementById('selectAllBtn').textContent = allSelected ? 'Deselect all' : 'Select all';
  }

  async function pickFolder() {
    const r = await fetch('/api/project-init/pickFolder', { method: 'POST' });
    const j = await r.json();
    if (j.path) document.getElementById('destFolder').value = j.path;
  }

  async function openUrl(url) {
    await fetch('/api/open', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ url }),
    });
  }

  async function initProject() {
    const checked = files.filter((_, i) => document.getElementById('cb_' + i)?.checked);
    if (!checked.length) { setStatus('No files selected.', 'err'); return; }
    const destFolder = document.getElementById('destFolder').value.trim();
    if (!destFolder) { setStatus('Please select a destination folder first.', 'err'); return; }
    const el = document.getElementById('status');
    el.textContent = 'Downloading ' + checked.length + ' file(s)…';
    el.className = 'status-panel is-busy';
    try {
      const r = await fetch('/api/project-init/download', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ files: checked, destFolder }),
      });
      const j = await r.json();
      setStatus(j.message, j.ok ? 'ok' : 'err');
    } catch (e) {
      setStatus('Error: ' + (e.message || e), 'err');
    }
  }

  function setStatus(text, cls) {
    const el = document.getElementById('status');
    el.textContent = text;
    el.className = 'status-panel' + (cls ? ' ' + cls : '');
  }

  refresh();
</script>
`
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	_, _ = w.Write([]byte(Page("/project-init", "Initialize Project", body)))
}

func htmlEscape(s string) string {
	s = strings.ReplaceAll(s, "&", "&amp;")
	s = strings.ReplaceAll(s, `"`, "&quot;")
	s = strings.ReplaceAll(s, "<", "&lt;")
	s = strings.ReplaceAll(s, ">", "&gt;")
	return s
}

func ProjectInitManifestEndpoint(w http.ResponseWriter, r *http.Request) {
	manifestURL := getManifestURL()
	entries, err := fetchManifest(manifestURL)
	if err != nil {
		writeJSON(w, map[string]any{"error": err.Error()})
		return
	}
	writeJSON(w, map[string]any{"files": entries, "manifestUrl": manifestURL})
}

func ProjectInitPickFolderEndpoint(w http.ResponseWriter, r *http.Request) {
	cfg := LoadConfig()
	folder := PickFolder("Select Destination Folder", cfg.LastPickDir)
	if folder == "" {
		writeJSON(w, map[string]any{"path": ""})
		return
	}
	cfg.LastPickDir = folder
	_ = SaveConfig(cfg)
	writeJSON(w, map[string]any{"path": folder})
}

func ProjectInitSetManifestURLEndpoint(w http.ResponseWriter, r *http.Request) {
	var req struct {
		URL string `json:"url"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
		return
	}
	cfg := LoadConfig()
	cfg.ProjectInitManifestURL = strings.TrimSpace(req.URL)
	if err := SaveConfig(cfg); err != nil {
		writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
		return
	}
	writeJSON(w, map[string]any{"ok": true})
}

func ProjectInitDownloadEndpoint(w http.ResponseWriter, r *http.Request) {
	var req struct {
		Files      []ManifestEntry `json:"files"`
		DestFolder string          `json:"destFolder"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, map[string]any{"ok": false, "message": "Invalid request: " + err.Error()})
		return
	}
	if req.DestFolder == "" {
		writeJSON(w, map[string]any{"ok": false, "message": "No destination folder specified."})
		return
	}
	var errs []string
	for _, f := range req.Files {
		if err := downloadManifestFile(f.URL, filepath.Join(req.DestFolder, f.Filename)); err != nil {
			errs = append(errs, f.Filename+": "+err.Error())
		}
	}
	total := len(req.Files)
	if len(errs) > 0 {
		writeJSON(w, map[string]any{
			"ok":      false,
			"message": fmt.Sprintf("%d/%d downloaded.\n\nErrors:\n%s", total-len(errs), total, strings.Join(errs, "\n")),
		})
	} else {
		writeJSON(w, map[string]any{
			"ok":      true,
			"message": fmt.Sprintf("Done! %d file%s downloaded to: %s", total, pluralS(total), req.DestFolder),
		})
	}
}