import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import { AlertTriangle, BookUser, ChevronDown, FileText, FolderOpen, Maximize2, Minimize2, Minus, MoreVertical, Paperclip, Send, Trash2, X, Type, Clock, CheckCheck, ChevronsDown } from "lucide-react";
import { useCompose, type Draft } from "@/store/compose";
import { useMail } from "@/store/mail";
import { useSettings } from "@/store/settings";
import { visibleIdentities } from "@/lib/identityVisibility";
import { RecipientInput } from "./RecipientInput";
import { RichEditor, type RichEditorHandle } from "./RichEditor";
import { MenuItem, MenuSep, MenuTitle, Popover, useMenu } from "@/ui/popover";
import { confirmDialog, promptDialog } from "@/ui/dialog";
import { formatSize, formatRelative } from "@/lib/format";
import { htmlToText, textToHtml } from "@/lib/text";
import { isValidEmail } from "@/lib/address";
import { attachmentIcon } from "../mail/MessageView";
import { FilePicker } from "./FilePicker";
import { RecipientPicker, type Field } from "./RecipientPicker";
import { useFiles } from "@/store/files";
import { keyboard } from "@/lib/keyboard";
import { useIsMobile } from "@/ui/misc";
import { toast } from "@/ui/toast";
import { ScheduleDialog, ScheduleMenuItems } from "./SchedulePicker";
import { scheduleSupported, scheduleWindowMs } from "@/store/scheduled";
import { formatScheduleTime } from "@/lib/schedule";
import { t as translate } from "@/lib/i18n";

export function Composer({ draft }: { draft: Draft }) {
  const update = useCompose((s) => s.update);
  const close = useCompose((s) => s.close);
  const send = useCompose((s) => s.send);
  const saveDraft = useCompose((s) => s.saveDraft);
  const addFiles = useCompose((s) => s.addFiles);
  const addFromFiles = useCompose((s) => s.addFromFiles);
  const filesAvailable = useFiles((s) => s.available);
  const [pickerOpen, setPickerOpen] = useState(false);
  const [addressBookOpen, setAddressBookOpen] = useState(false);
  const removeAttachment = useCompose((s) => s.removeAttachment);
  const setIdentity = useCompose((s) => s.setIdentity);
  const insertTemplate = useCompose((s) => s.insertTemplate);
  const focus = useCompose((s) => s.focus);
  const allIdentities = useMail((s) => s.identities);
  const mailAccountId = useMail((s) => s.accountId);
  const hiddenIdentities = useSettings((s) => s.settings.hiddenIdentities);
  const defaultIdentityId = useSettings((s) => (mailAccountId ? s.settings.defaultIdentityByAccount[mailAccountId] : undefined));
  const settings = useSettings((s) => s.settings);
  const updateSettings = useSettings((s) => s.update);
  const isMobile = useIsMobile();
  const editorRef = useRef<RichEditorHandle>(null);
  const fileRef = useRef<HTMLInputElement>(null);
  const [dropping, setDropping] = useState(false);
  const moreMenu = useMenu();
  const sendMenu = useMenu();
  const templateMenu = useMenu();
  const [showToolbar, setShowToolbar] = useState(true);
  const [scheduleOpen, setScheduleOpen] = useState(false);
  // Read once per render from the session; it cannot change while a composer is open.
  const canSchedule = scheduleSupported();
  const scheduleMax = canSchedule ? scheduleWindowMs() : 0;
  const d = draft;
  const key = d.key;
  // Where the caret starts, decided once when the composer opens: a blank
  // message starts in the recipients, a reply (already addressed and titled)
  // starts in the body. Deriving this from live state would move the caret
  // while the user types.
  const [initialFocus] = useState(() => initialFocusTarget(draft));

  const patch = useCallback((p: Partial<Draft>) => update(key, p), [update, key]);
  const onHtml = useCallback((html: string) => update(key, { html }), [update, key]);

  // Esc closes (saves draft); Ctrl+Enter sends
  useEffect(() => {
    if (d.minimized) return;
    return keyboard.pushScope("composer", [
      { keys: "mod+enter", description: "Send message", group: "Compose", handler: () => void doSend(), allowInInput: true },
      { keys: "esc", description: "Close composer (saves draft)", group: "Compose", handler: () => { if (document.activeElement?.closest(".composer")) { void close(key); return true; } return false; }, allowInInput: true },
      { keys: "mod+s", description: "Save draft", group: "Compose", handler: () => { void saveDraft(key); }, allowInInput: true },
    ]);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [key, d.minimized]);

  const bodyText = useMemo(() => (d.format === "html" ? htmlToText(d.html.replace(/<div class="ihm-quote">[\s\S]*$/, "")) : d.text), [d.html, d.text, d.format]);

  const doSend = async () => {
    const all = [...d.to, ...d.cc, ...d.bcc];
    if (!all.length) {
      toast.error("Please add at least one recipient");
      return;
    }
    const bad = all.filter((a) => !isValidEmail(a.email));
    if (bad.length) {
      toast.error(`Invalid address: ${bad[0]!.email}`);
      return;
    }
    if (d.attachments.some((a) => a.error)) {
      toast.error("Remove attachments that failed to upload first");
      return;
    }
    if (d.attachments.some((a) => !a.blobId)) {
      toast.error("Attachments are still uploading");
      return;
    }
    if (!d.subject.trim()) {
      const ok = await confirmDialog({ title: "Send without a subject?", confirmLabel: "Send anyway" });
      if (!ok) return;
    }
    if (settings.attachmentReminder && !d.attachments.length && /\b(attach(ed|ment|ing)?|enclosed|anbei|ci-joint|adjunto)\b/i.test(bodyText) ) {
      const ok = await confirmDialog({ title: "Did you forget the attachment?", message: "Your message mentions an attachment, but nothing is attached.", confirmLabel: "Send anyway" });
      if (!ok) return;
    }
    await send(key);
  };

  const scheduleFor = (at: Date) => {
    sendMenu.close();
    setScheduleOpen(false);
    patch({ sendAt: at.getTime() });
  };

  const toggleFormat = () => {
    if (d.format === "html") {
      patch({ format: "text", text: htmlToText(d.html) });
    } else {
      patch({ format: "html", html: textToHtml(d.text, { linkify: false, quoteColors: false }).replace(/\n/g, "<br>") });
    }
  };

  const onDrop = (e: React.DragEvent) => {
    e.preventDefault();
    setDropping(false);
    const files = Array.from(e.dataTransfer.files);
    if (files.length) addFiles(key, files);
  };

  /*
   * The picker offers the visible identities, plus two that can never be
   * hidden from it: the one this draft is already using, and the default a new
   * draft starts on. Hiding either would leave the select with no matching
   * option and silently move the From line. See lib/identityVisibility.
   */
  const identities = useMemo(
    () => visibleIdentities(allIdentities, hiddenIdentities, [d.identityId, defaultIdentityId]),
    [allIdentities, hiddenIdentities, d.identityId, defaultIdentityId],
  );
  const ident = identities.find((i) => i.id === d.identityId) ?? identities[0];
  const title = d.subject || (d.replyMode ? (d.replyMode === "forward" ? "Forward" : "Reply") : "New message");
  const status = d.sending ? "Sending…" : d.saving ? "Saving…" : d.error ? "Error" : d.savedAt ? `Saved ${formatRelative(new Date(d.savedAt).toISOString())}` : d.dirty ? "Unsaved" : "";
  const totalSize = d.attachments.reduce((n, a) => n + a.size, 0);

  if (d.minimized) {
    return (
      <div className="composer minimized" onClick={() => focus(key)}>
        <div className="composer-head">
          <span className="title">{title}</span>
          <button className="icon-btn sm" aria-label={translate("Restore")} onClick={(e) => { e.stopPropagation(); focus(key); }}><Maximize2 size={16} /></button>
          <button className="icon-btn sm" aria-label={translate("Close")} onClick={(e) => { e.stopPropagation(); void close(key); }}><X size={16} /></button>
        </div>
      </div>
    );
  }

  return (
    <div className={`composer ${d.maximized ? "maximized" : ""} ${dropping ? "dropping" : ""}`} onDragOver={(e) => { if (e.dataTransfer.types.includes("Files")) { e.preventDefault(); setDropping(true); } }} onDragLeave={() => setDropping(false)} onDrop={onDrop} role="dialog" aria-label={translate("Compose message")}>
      <div className="composer-head" onDoubleClick={() => patch({ maximized: !d.maximized })}>
        <span className="title">{title}</span>
        <span className="status">{status}</span>
        {!isMobile && <button className="icon-btn sm" aria-label={translate("Minimize")} title={translate("Minimize")} onClick={() => patch({ minimized: true })}><Minus size={16} /></button>}
        {!isMobile && <button className="icon-btn sm" aria-label={d.maximized ? "Restore" : "Maximize"} title={d.maximized ? "Restore" : "Full screen"} onClick={() => patch({ maximized: !d.maximized })}>{d.maximized ? <Minimize2 size={16} /> : <Maximize2 size={16} />}</button>}
        <button className="icon-btn sm" aria-label={translate("Close")} title={translate("Save & close (Esc)")} onClick={() => void close(key)}><X size={18} /></button>
      </div>
      <div className="composer-body">
        <div className="composer-fields">
          {identities.length > 1 && (
            <div className="composer-field">
              <label>{translate("From")}</label>
              <select className="from-select" value={ident?.id ?? ""} onChange={(e) => setIdentity(key, e.target.value)}>
                {identities.map((i) => <option key={i.id} value={i.id}>{i.name ? `${i.name} <${i.email}>` : i.email}</option>)}
              </select>
            </div>
          )}
          <div className="composer-field">
            <label htmlFor={`${key}-to`}>
              {/* Opens the address books. Autocomplete only helps someone who
                  already knows the name they are half-way through typing. */}
              <button type="button" className="link-btn" onClick={() => setAddressBookOpen(true)} title={translate("Choose from address books")}>{translate("To")}</button>
            </label>
            <RecipientInput id={`${key}-to`} value={d.to} onChange={(to) => patch({ to })} placeholder={translate("Recipients")} autoFocus={initialFocus === "to"} />
            <span className="field-extra">
              {/* Beside Cc and Bcc, because that is where someone looks when
                  they are thinking about who the message goes to. The label
                  opens it too, for anyone who tries that first. */}
              <button type="button" onClick={() => setAddressBookOpen(true)} title={translate("Choose from address books")} aria-label={translate("Choose from address books")}><BookUser size={15} /></button>
              {!d.showCc && <button type="button" onClick={() => patch({ showCc: true })}>{translate("Cc")}</button>}
              {!d.showBcc && <button type="button" onClick={() => patch({ showBcc: true })}>{translate("Bcc")}</button>}
              {!d.showReplyTo && <button type="button" onClick={() => patch({ showReplyTo: true })} title={translate("Set a Reply-To address")}>{translate("Reply-To")}</button>}
            </span>
          </div>
          {d.showReplyTo && (
            <div className="composer-field">
              <label htmlFor={`${key}-rt`} title={translate("Replies will go to this address instead of the From address")}>{translate("Reply-To")}</label>
              <RecipientInput id={`${key}-rt`} value={d.replyTo} onChange={(replyTo) => patch({ replyTo })} placeholder={translate("Replies go to…")} />
            </div>
          )}
          {d.showCc && (
            <div className="composer-field">
              <label htmlFor={`${key}-cc`}>{translate("Cc")}</label>
              <RecipientInput id={`${key}-cc`} value={d.cc} onChange={(cc) => patch({ cc })} />
            </div>
          )}
          {d.showBcc && (
            <div className="composer-field">
              <label htmlFor={`${key}-bcc`}>{translate("Bcc")}</label>
              <RecipientInput id={`${key}-bcc`} value={d.bcc} onChange={(bcc) => patch({ bcc })} />
            </div>
          )}
          <div className="composer-field">
            <label htmlFor={`${key}-subj`} className="sr-only">{translate("Subject")}</label>
            <input id={`${key}-subj`} className="plain" placeholder={translate("Subject")} value={d.subject} onChange={(e) => patch({ subject: e.target.value })} autoFocus={initialFocus === "subject"} />
            {d.priority !== "normal" && <span className="tag" style={{ background: d.priority === "high" ? "var(--danger)" : "var(--fg-faint)" }}>{d.priority === "high" ? "High priority" : "Low priority"}</span>}
            {d.requestReceipt && <span className="tag" style={{ background: "var(--accent)" }} title={translate("Read receipt requested")}><CheckCheck size={12} /></span>}
            {d.sendAt !== null && (
              <button type="button" className="tag" style={{ background: "var(--accent)" }} title={translate("Scheduled — click to clear the schedule")} onClick={() => patch({ sendAt: null })}>
                <Clock size={12} /> {formatScheduleTime(new Date(d.sendAt))} <X size={12} />
              </button>
            )}
          </div>
        </div>
        {d.format === "html" ? (
          <RichEditor ref={editorRef} html={d.html} onChange={onHtml} placeholder={translate("Write your message…")} spellcheck={settings.spellcheck} onFiles={(files) => addFiles(key, files)} showToolbar={showToolbar} autoFocus={initialFocus === "body"} />
        ) : (
          <textarea className="editor-textarea" value={d.text} onChange={(e) => patch({ text: e.target.value })} placeholder={translate("Write your message…")} spellCheck={settings.spellcheck} />
        )}
        {d.attachments.some((a) => !a.inline) && (
          <div className="composer-attachments">
            {d.attachments.filter((a) => !a.inline).map((a) => (
              <div key={a.id} className={`attachment ${a.error ? "error" : ""}`} title={a.error ?? a.name}>
                <span className="att-icon">{attachmentIcon(a.type, a.name)}</span>
                <span className="att-text">
                  <span className="att-name">{a.name}</span>
                  <span className="att-size">{a.error ? <span style={{ color: "var(--danger)" }}>{a.error}</span> : a.blobId ? formatSize(a.size) : `${a.progress}%`}{a.inline ? " · inline" : ""}</span>
                </span>
                <button className="icon-btn xs" aria-label={translate("Remove attachment")} onClick={() => removeAttachment(key, a.id)}><X size={14} /></button>
                {!a.blobId && !a.error && <span className="att-progress" style={{ width: `${a.progress}%` }} />}
              </div>
            ))}
          </div>
        )}
        <div className="composer-foot">
          <span className="send-group">
            <button className="btn btn-primary" onClick={() => void doSend()} disabled={d.sending} title={d.sendAt !== null ? `Hand to the server, held until ${formatScheduleTime(new Date(d.sendAt))} (Ctrl+Enter)` : "Send (Ctrl+Enter)"}>
              {d.sendAt !== null ? <><Clock size={16} /> Schedule send</> : <><Send size={16} /> Send</>}
            </button>
            <button className="btn btn-primary" onClick={sendMenu.open} aria-label={translate("Send options")}><ChevronDown size={16} /></button>
          </span>
          <Popover anchor={sendMenu.anchor} onClose={sendMenu.close} side="top" width={280}>
            <MenuItem icon={<Send size={16} />} label={d.sendAt !== null ? "Send now instead" : "Send"} kbd={d.sendAt !== null ? undefined : "Ctrl+↵"} onClick={() => { if (d.sendAt !== null) patch({ sendAt: null }); sendMenu.close(); void doSend(); }} />
            <MenuItem icon={<Clock size={16} />} label={`Undo window: ${settings.undoSendSeconds}s`} onClick={() => updateSettings({ undoSendSeconds: settings.undoSendSeconds >= 30 ? 0 : settings.undoSendSeconds + 5 })} />
            {canSchedule && <ScheduleMenuItems maxMs={scheduleMax} onPick={scheduleFor} onCustom={() => { sendMenu.close(); setScheduleOpen(true); }} />}
          </Popover>
          {addressBookOpen && (
            <RecipientPicker
              onPick={(field: Field, addresses) => {
                // Added to whatever is already there, and the field is opened if
                // it was hidden -- picking a Bcc should not put one somewhere
                // the writer cannot see it.
                const existing = field === "to" ? d.to : field === "cc" ? d.cc : d.bcc;
                const merged = [...existing];
                for (const a of addresses) if (!merged.some((x) => x.email.toLowerCase() === a.email.toLowerCase())) merged.push(a);
                patch({ [field]: merged, ...(field === "cc" ? { showCc: true } : field === "bcc" ? { showBcc: true } : {}) });
              }}
              onClose={() => setAddressBookOpen(false)}
            />
          )}
          {pickerOpen && <FilePicker onPick={(picked) => void addFromFiles(key, picked)} onClose={() => setPickerOpen(false)} />}
          {canSchedule && scheduleOpen && (
            <ScheduleDialog open maxMs={scheduleMax} initial={d.sendAt} onClose={() => setScheduleOpen(false)} onPick={scheduleFor} />
          )}
          <span className="more-actions">
            <button className="icon-btn" title={translate("Attach files")} onClick={() => fileRef.current?.click()}><Paperclip size={18} /></button>
            {filesAvailable && <button className="icon-btn" title={translate("Attach from Files")} onClick={() => setPickerOpen(true)}><FolderOpen size={18} /></button>}
            <input ref={fileRef} type="file" multiple hidden onChange={(e) => { const files = Array.from(e.target.files ?? []); if (files.length) addFiles(key, files); e.target.value = ""; }} />
            {d.format === "html" && <button className={`icon-btn ${showToolbar ? "active" : ""}`} title={translate("Formatting options")} onClick={() => setShowToolbar((v) => !v)}><Type size={18} /></button>}
            {settings.templates.length > 0 && <button className="icon-btn" title={translate("Insert template")} onClick={templateMenu.open}><FileText size={18} /></button>}
            <Popover anchor={templateMenu.anchor} onClose={templateMenu.close} side="top" width={260}>
              <MenuTitle>{translate("Templates")}</MenuTitle>
              {settings.templates.map((t) => <MenuItem key={t.id} label={t.name} onClick={() => insertTemplate(key, t.html, t.subject)} />)}
            </Popover>
            <button className="icon-btn" onClick={moreMenu.open} aria-label={translate("More options")}><MoreVertical size={18} /></button>
            <Popover anchor={moreMenu.anchor} onClose={moreMenu.close} side="top" width={260}>
              <MenuItem icon={<Type size={16} />} label={d.format === "html" ? "Switch to plain text" : "Switch to rich text"} onClick={toggleFormat} />
              <MenuItem icon={<CheckCheck size={16} />} label={translate("Request read receipt")} checked={d.requestReceipt} onClick={() => patch({ requestReceipt: !d.requestReceipt })} />
              <MenuSep />
              <MenuTitle>{translate("Priority")}</MenuTitle>
              <MenuItem label={translate("High")} checked={d.priority === "high"} onClick={() => patch({ priority: "high" })} />
              <MenuItem label={translate("Normal")} checked={d.priority === "normal"} onClick={() => patch({ priority: "normal" })} />
              <MenuItem label={translate("Low")} checked={d.priority === "low"} onClick={() => patch({ priority: "low" })} />
              <MenuSep />
              <MenuItem icon={<ChevronsDown size={16} />} label={translate("Save as template")} onClick={async () => { const name = await promptDialog({ title: "Save as template", defaultValue: d.subject || "Template", placeholder: "Template name" }); if (name) updateSettings({ templates: [...useSettings.getState().settings.templates, { id: `t${Date.now()}`, name, subject: d.subject, html: d.format === "html" ? d.html : textToHtml(d.text) }] }); }} />
              <MenuItem icon={<FileText size={16} />} label={translate("Save draft now")} onClick={() => void saveDraft(key)} />
            </Popover>
          </span>
          <span className="spacer" />
          {totalSize > 20 * 1024 * 1024 && <span className="hint row gap-4" title={translate("Large attachments may be rejected by some servers")}><AlertTriangle size={14} /> {formatSize(totalSize)}</span>}
          <button className="icon-btn danger" title={translate("Discard draft")} aria-label={translate("Discard draft")} onClick={async () => { if (!d.dirty && !d.draftId) { void close(key, { discard: true }); return; } if (await confirmDialog({ title: "Discard this draft?", confirmLabel: "Discard", danger: true })) void close(key, { discard: true }); }}><Trash2 size={18} /></button>
        </div>
      </div>
    </div>
  );
}

export type FocusTarget = "to" | "subject" | "body";

/** Which field a freshly opened composer should put the caret in. */
export function initialFocusTarget(d: Pick<Draft, "to" | "subject">): FocusTarget {
  if (!d.to.length) return "to";
  if (!d.subject) return "subject";
  return "body";
}