import { useEffect, useState } from 'react';
import type { ReactNode } from 'react';
import { ChevronDown, ChevronRight, Copy, RefreshCw, Check, Share2, RotateCw, GitFork, Trash2, PanelRightOpen } from 'lucide-react';
import { toast } from 'sonner';
import type { Chat, ErrorReason, Message } from '@/api/types';
import { api, ApiError } from '@/api/client';
import { sessionEvents } from '@/hooks/sessionEvents';
import { sendToTerminal, terminalsRegistry, type TerminalRegistration } from '@/lib/events';
import { CapHitSentinel } from './CapHitSentinel';
import { DoomLoopSentinel } from './DoomLoopSentinel';
import { MarkdownRenderer } from './MarkdownRenderer';
import { Button } from '@/components/ui/button';
import {
  ContextMenu,
  ContextMenuContent,
  ContextMenuItem,
  ContextMenuSeparator,
  ContextMenuSub,
  ContextMenuSubContent,
  ContextMenuSubTrigger,
  ContextMenuTrigger,
} from '@/components/ui/context-menu';
import {
  Dialog,
  DialogContent,
  DialogDescription,
  DialogFooter,
  DialogHeader,
  DialogTitle,
} from '@/components/ui/dialog';

// v1.10 booterm: tiny subscription hook for the mounted-terminals registry.
// Used by the right-click "Send to terminal" submenu so it always reflects
// currently-open terminal panes without prop drilling from Workspace.
function useTerminals(): TerminalRegistration[] {
  const [list, setList] = useState(() => terminalsRegistry.list());
  useEffect(() => terminalsRegistry.subscribe(() => setList(terminalsRegistry.list())), []);
  return list;
}

// Wrap a message body with a right-click context menu offering Copy and
// "Send to terminal → <pane name>". Send is disabled when nothing is
// selected or no terminal panes are open; clicking a target emits a
// sendToTerminal event that TerminalPane subscribes to (filtered by pane_id).
function SendToTerminalMenu({ children }: { children: ReactNode }) {
  const [selection, setSelection] = useState('');
  const terminals = useTerminals();
  const hasSelection = selection.length > 0;
  const canSend = hasSelection && terminals.length > 0;

  return (
    <ContextMenu
      onOpenChange={(open) => {
        if (open) {
          const sel = typeof window !== 'undefined' ? window.getSelection()?.toString() ?? '' : '';
          setSelection(sel);
        }
      }}
    >
      <ContextMenuTrigger asChild>{children}</ContextMenuTrigger>
      <ContextMenuContent>
        <ContextMenuItem
          disabled={!hasSelection}
          onSelect={() => {
            void navigator.clipboard.writeText(selection).catch((err) => {
              toast.error(err instanceof Error ? err.message : 'copy failed');
            });
          }}
        >
          Copy
        </ContextMenuItem>
        <ContextMenuSeparator />
        <ContextMenuSub>
          <ContextMenuSubTrigger disabled={!canSend}>Send to terminal</ContextMenuSubTrigger>
          <ContextMenuSubContent>
            {terminals.length === 0 ? (
              <ContextMenuItem disabled>No terminal panes open</ContextMenuItem>
            ) : (
              terminals.map((t) => (
                <ContextMenuItem
                  key={t.paneId}
                  onSelect={() => sendToTerminal.emit({ pane_id: t.paneId, text: selection })}
                >
                  {t.label}
                </ContextMenuItem>
              ))
            )}
          </ContextMenuSubContent>
        </ContextMenuSub>
      </ContextMenuContent>
    </ContextMenu>
  );
}

// v1.8.2: human labels for the machine-readable error reasons that ride on
// failed assistant messages via metadata.kind === 'error'. Kept short so the
// inline render under "message failed" stays a single muted line.
const ERROR_REASON_LABELS: Record<ErrorReason, string> = {
  llm_provider_error: 'LLM provider error',
  tool_execution_failed: 'Tool execution failed',
  summary_after_cap_failed: 'Summary after tool budget hit failed',
};

// v1.14.x-html-artifact-panes: MarkdownBody and its path-linkifier helpers
// moved to apps/web/src/components/MarkdownRenderer.tsx so the new artifact
// panes can render assistant content with the same Shiki + remark-gfm setup.

// Pane-header title derivation for a markdown artifact. Order matches the
// server slug logic in services/artifacts.ts: first `# ` heading → first 6
// words of the body → 'Markdown artifact'. Truncated to keep the pane header
// readable.
function deriveMarkdownTitle(content: string): string {
  const headingMatch = content.match(/^\s*#\s+(.+?)\s*$/m);
  if (headingMatch && headingMatch[1]) return headingMatch[1].slice(0, 80);
  const words = content.trim().split(/\s+/).slice(0, 6).join(' ');
  if (words) return words.slice(0, 80);
  return 'Markdown artifact';
}

interface Props {
  message: Message;
  sessionChats?: Chat[];
  // v1.8.2: passed by MessageList's render-item pass for cap-hit sentinels.
  // Only the most recent sentinel shows the Continue button.
  capHitInfo?: { position: number; isLatest: boolean };
}

function StatsLine({ message }: { message: Message }) {
  const tokens = message.tokens_used;
  if (typeof tokens !== 'number' || tokens <= 0) return null;
  const started = message.started_at ? Date.parse(message.started_at) : NaN;
  const finished = message.finished_at ? Date.parse(message.finished_at) : NaN;
  let tps: number | null = null;
  if (!Number.isNaN(started) && !Number.isNaN(finished) && finished > started) {
    const seconds = (finished - started) / 1000;
    if (seconds > 0) tps = Math.round((tokens / seconds) * 10) / 10;
  }
  const ctxUsed = message.ctx_used;
  const ctxMax = message.ctx_max;
  const ctxPart =
    typeof ctxUsed === 'number'
      ? typeof ctxMax === 'number' && ctxMax > 0
        ? `${ctxUsed} / ${ctxMax} ctx`
        : `${ctxUsed} ctx`
      : null;

  const parts: string[] = [`${tokens} tokens`];
  if (tps !== null) parts.push(`${tps.toFixed(1)} tok/s`);
  if (ctxPart) parts.push(ctxPart);

  return (
    <div className="text-[10px] font-mono text-muted-foreground">
      {parts.join(' · ')}
    </div>
  );
}

function ActionRow({
  message,
}: {
  message: Message;
}) {
  const [justCopied, setJustCopied] = useState(false);
  const [regenerating, setRegenerating] = useState(false);
  const [forking, setForking] = useState(false);
  const [deleteOpen, setDeleteOpen] = useState(false);
  const [deleting, setDeleting] = useState(false);

  async function copy() {
    try {
      await navigator.clipboard.writeText(message.content);
      setJustCopied(true);
      setTimeout(() => setJustCopied(false), 1200);
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'copy failed');
    }
  }

  async function regenerate() {
    if (regenerating || message.status === 'streaming') return;
    setRegenerating(true);
    try {
      await api.messages.regenerate(message.chat_id, message.id);
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'regenerate failed');
    } finally {
      setRegenerating(false);
    }
  }

  async function fork() {
    if (forking || message.status !== 'complete') return;
    setForking(true);
    try {
      const chat = await api.chats.fork(message.chat_id, { messageId: message.id });
      sessionEvents.emit({ type: 'open_chat_in_active_pane', chat_id: chat.id });
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'fork failed');
    } finally {
      setForking(false);
    }
  }

  async function confirmDelete() {
    if (deleting) return;
    setDeleting(true);
    try {
      await api.messages.remove(message.chat_id, message.id);
      setDeleteOpen(false);
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'delete failed');
    } finally {
      setDeleting(false);
    }
  }

  const isAssistant = message.role === 'assistant';
  const canRegen = isAssistant && message.status !== 'streaming';
  const canFork = message.status === 'complete';
  const canDelete = message.status !== 'streaming';
  const [openingPane, setOpeningPane] = useState(false);

  // v1.14.x-html-artifact-panes: probe for an html_artifact part. If present,
  // open the HTML pane variant; otherwise fall back to the markdown variant.
  // Title derivation for markdown: first `# ` heading → first 6 words of the
  // body → 'Markdown artifact' (mirrors the slug logic in
  // services/artifacts.ts).
  async function openInPane() {
    if (openingPane || message.status === 'streaming') return;
    setOpeningPane(true);
    try {
      try {
        const payload = await api.messages.getHtmlArtifact(
          message.chat_id,
          message.id,
        );
        sessionEvents.emit({
          type: 'open_html_artifact_pane',
          state: {
            chat_id: message.chat_id,
            message_id: message.id,
            title: payload.title,
          },
        });
        return;
      } catch (err) {
        // 404 (no html_artifact part) is the expected fall-through path —
        // markdown variant opens below. Any other error (network, 500) is
        // a real failure; toast and bail rather than masquerading as markdown.
        const status = err instanceof ApiError ? err.status : null;
        if (status !== 404) {
          toast.error(err instanceof Error ? err.message : 'open in pane failed');
          return;
        }
      }
      const title = deriveMarkdownTitle(message.content);
      sessionEvents.emit({
        type: 'open_markdown_artifact_pane',
        state: {
          chat_id: message.chat_id,
          message_id: message.id,
          title,
        },
      });
    } finally {
      setOpeningPane(false);
    }
  }

  return (
    <>
      <div className="flex gap-1 opacity-0 group-hover:opacity-100 transition-opacity max-md:opacity-100">
        <button
          type="button"
          onClick={() => void copy()}
          className="inline-flex items-center justify-center size-6 rounded text-muted-foreground hover:bg-muted hover:text-foreground max-md:min-h-[44px] max-md:min-w-[44px]"
          aria-label="Copy message"
          title="Copy"
        >
          {justCopied ? <Check className="size-3" /> : <Copy className="size-3" />}
        </button>
        {isAssistant && (
          <button
            type="button"
            onClick={() => void openInPane()}
            disabled={openingPane || message.status === 'streaming'}
            className="inline-flex items-center justify-center size-6 rounded text-muted-foreground hover:bg-muted hover:text-foreground disabled:opacity-40 disabled:cursor-not-allowed max-md:min-h-[44px] max-md:min-w-[44px]"
            aria-label="Open in pane"
            title="Open in pane"
          >
            <PanelRightOpen className="size-3" />
          </button>
        )}
        {isAssistant && (
          <button
            type="button"
            onClick={() => void regenerate()}
            disabled={!canRegen || regenerating}
            className="inline-flex items-center justify-center size-6 rounded text-muted-foreground hover:bg-muted hover:text-foreground disabled:opacity-40 disabled:cursor-not-allowed max-md:min-h-[44px] max-md:min-w-[44px]"
            aria-label="Regenerate message"
            title="Regenerate"
          >
            <RefreshCw className={`size-3 ${regenerating ? 'animate-spin' : ''}`} />
          </button>
        )}
        <button
          type="button"
          onClick={() => void fork()}
          disabled={!canFork || forking}
          className="inline-flex items-center justify-center size-6 rounded text-muted-foreground hover:bg-muted hover:text-foreground disabled:opacity-40 disabled:cursor-not-allowed max-md:min-h-[44px] max-md:min-w-[44px]"
          aria-label="Fork from here"
          title="Fork from here"
        >
          <GitFork className="size-3" />
        </button>
        <button
          type="button"
          onClick={() => setDeleteOpen(true)}
          disabled={!canDelete}
          className="inline-flex items-center justify-center size-6 rounded text-muted-foreground hover:bg-muted hover:text-destructive disabled:opacity-40 disabled:cursor-not-allowed max-md:min-h-[44px] max-md:min-w-[44px]"
          aria-label="Delete message"
          title="Delete message"
        >
          <Trash2 className="size-3" />
        </button>
      </div>
      <Dialog
        open={deleteOpen}
        onOpenChange={(open) => {
          if (!deleting) setDeleteOpen(open);
        }}
      >
        <DialogContent>
          <DialogHeader>
            <DialogTitle>Delete this message and all messages after it?</DialogTitle>
            <DialogDescription>
              This removes the selected message and every later message in this chat. This cannot be undone.
            </DialogDescription>
          </DialogHeader>
          <DialogFooter>
            <Button
              variant="outline"
              onClick={() => setDeleteOpen(false)}
              disabled={deleting}
            >
              Cancel
            </Button>
            <Button
              variant="destructive"
              onClick={() => void confirmDelete()}
              disabled={deleting}
            >
              {deleting ? 'Deleting…' : 'Delete'}
            </Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </>
  );
}

function CompactCard({ message, sessionChats }: { message: Message; sessionChats?: Chat[] }) {
  const [expanded, setExpanded] = useState(false);
  const [copied, setCopied] = useState(false);
  const [shareOpen, setShareOpen] = useState(false);
  const [rerunning, setRerunning] = useState(false);

  const headerMatch = message.content.match(/^\[Context compacted — (\d+) messages summarized\]/);
  const headerText = headerMatch ? headerMatch[0] : 'Context compacted';
  const summaryText = headerMatch
    ? message.content.slice(headerMatch[0].length).trim()
    : message.content;

  async function handleCopy() {
    try {
      await navigator.clipboard.writeText(summaryText);
      setCopied(true);
      setTimeout(() => setCopied(false), 1200);
      toast.success('Summary copied to clipboard');
    } catch {
      toast.error('Copy failed');
    }
  }

  async function handleShareToChat(chat: Chat) {
    try {
      await api.messages.send(chat.id, summaryText);
      toast.success(`Summary sent to ${chat.name ?? 'New chat'}`);
      setShareOpen(false);
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'Failed to share');
    }
  }

  async function handleRerun() {
    if (rerunning) return;
    setRerunning(true);
    try {
      await api.chats.compact(message.chat_id);
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'Re-run failed');
    } finally {
      setRerunning(false);
    }
  }

  const otherChats = (sessionChats ?? []).filter(
    (c) => c.id !== message.chat_id && c.status === 'open'
  );

  return (
    <div className="rounded-lg border bg-muted/30 text-sm">
      <div className="flex items-center gap-2 px-3 py-2">
        <button
          type="button"
          onClick={() => setExpanded(!expanded)}
          className="flex items-center gap-1.5 flex-1 min-w-0 text-left text-muted-foreground hover:text-foreground"
        >
          {expanded ? <ChevronDown size={14} /> : <ChevronRight size={14} />}
          <span className="text-xs font-medium truncate">{headerText}</span>
        </button>
        <button
          type="button"
          onClick={() => void handleCopy()}
          className="p-1 rounded hover:bg-muted text-muted-foreground"
          aria-label="Copy summary"
          title="Copy summary"
        >
          {copied ? <Check size={12} /> : <Copy size={12} />}
        </button>
        <div className="relative">
          <button
            type="button"
            onClick={() => setShareOpen(!shareOpen)}
            className="p-1 rounded hover:bg-muted text-muted-foreground"
            aria-label="Send to chat"
            title="Send to chat"
          >
            <Share2 size={12} />
          </button>
          {shareOpen && (
            <div className="absolute right-0 top-full mt-1 z-50 bg-popover border rounded-md shadow-md min-w-[180px] py-1">
              {otherChats.length === 0 ? (
                <div className="px-3 py-1.5 text-xs text-muted-foreground">
                  No other chats in this session
                </div>
              ) : (
                otherChats.map((c) => (
                  <button
                    key={c.id}
                    type="button"
                    onClick={() => void handleShareToChat(c)}
                    className="w-full text-left px-3 py-1.5 text-xs hover:bg-accent truncate"
                  >
                    {c.name ?? 'New chat'}
                  </button>
                ))
              )}
            </div>
          )}
        </div>
        <button
          type="button"
          onClick={() => void handleRerun()}
          disabled={rerunning}
          className="p-1 rounded hover:bg-muted text-muted-foreground disabled:opacity-40"
          aria-label="Re-run compact"
          title="Re-run compact"
        >
          <RotateCw size={12} className={rerunning ? 'animate-spin' : ''} />
        </button>
      </div>
      {expanded && (
        <div className="px-3 pb-3 text-xs leading-relaxed text-muted-foreground whitespace-pre-wrap border-t pt-2">
          {summaryText}
        </div>
      )}
    </div>
  );
}

// v1.11 anchored rolling summary. Inserted by services/compaction.ts as a
// role='assistant', summary=true row. Distinct from legacy CompactCard
// (which renders the kind='compact' system rows produced by v1.10 /compact).
// Collapsed by default; header shows the timestamp; body renders the
// summary markdown when expanded. Copy button matches CompactCard's affordance.
function SummaryCard({ message }: { message: Message }) {
  const [expanded, setExpanded] = useState(false);
  const [copied, setCopied] = useState(false);

  // Use finished_at when available (that's when the summary actually landed);
  // fall back to created_at for any row missing it. Both are ISO strings.
  const ts = message.finished_at ?? message.created_at;
  const headerTs = ts ? new Date(ts).toLocaleString() : '';

  async function handleCopy() {
    try {
      await navigator.clipboard.writeText(message.content);
      setCopied(true);
      setTimeout(() => setCopied(false), 1200);
      toast.success('Summary copied to clipboard');
    } catch {
      toast.error('Copy failed');
    }
  }

  return (
    <div className="rounded-lg border border-primary/30 bg-primary/5 text-sm">
      <div className="flex items-center gap-2 px-3 py-2">
        <button
          type="button"
          onClick={() => setExpanded(!expanded)}
          className="flex items-center gap-1.5 flex-1 min-w-0 text-left text-muted-foreground hover:text-foreground"
        >
          {expanded ? <ChevronDown size={14} /> : <ChevronRight size={14} />}
          <span className="text-xs font-medium truncate">
            Compacted summary — {headerTs}
          </span>
        </button>
        <button
          type="button"
          onClick={() => void handleCopy()}
          className="p-1 rounded hover:bg-muted text-muted-foreground"
          aria-label="Copy summary"
          title="Copy summary"
        >
          {copied ? <Check size={12} /> : <Copy size={12} />}
        </button>
      </div>
      {expanded && (
        <div className="px-3 pb-3 text-xs leading-relaxed border-t pt-2">
          <MarkdownRenderer content={message.content} />
        </div>
      )}
    </div>
  );
}

export function MessageBubble({ message, sessionChats, capHitInfo }: Props) {
  // v1.11: anchored rolling summary row. Checked BEFORE the kind==='compact'
  // branch because summary=true never coexists with kind='compact' (new
  // compactions emit role='assistant' rows with kind='message'+summary=true).
  if (message.summary) {
    return <SummaryCard message={message} />;
  }
  if (message.kind === 'compact') {
    return <CompactCard message={message} sessionChats={sessionChats} />;
  }

  // v1.8.2: cap-hit sentinels render as a distinct system bubble with a
  // Continue button. MessageList's pre-render pass tags each sentinel with
  // its position; only the latest gets the actionable button.
  if (
    message.role === 'system' &&
    message.metadata?.kind === 'cap_hit' &&
    capHitInfo
  ) {
    return (
      <CapHitSentinel
        message={message}
        capHitPosition={capHitInfo.position}
        isLatest={capHitInfo.isLatest}
      />
    );
  }

  // v1.11.6: doom-loop sentinel. No Continue affordance — retrying with the
  // same tools would just re-loop. The card explains what tripped and
  // suggests next steps (new message angle / switch agents).
  if (message.role === 'system' && message.metadata?.kind === 'doom_loop') {
    return <DoomLoopSentinel message={message} />;
  }

  // v1.8.2: tool messages and assistant tool_calls are now rendered by
  // MessageList via ToolCallLine / ToolCallGroup. Tool-role messages reach
  // this point only if MessageList didn't consume them (shouldn't happen,
  // but guard against it by rendering nothing rather than a stale card).
  if (message.role === 'tool') return null;

  if (message.role === 'user') {
    return (
      <div className="group flex flex-col items-end gap-1">
        <SendToTerminalMenu>
          <div className="max-w-[80%] rounded-lg bg-primary text-primary-foreground px-3 py-2 text-sm whitespace-pre-wrap break-words min-w-0">
            {message.content}
          </div>
        </SendToTerminalMenu>
        <ActionRow message={message} />
      </div>
    );
  }

  const isStreaming = message.status === 'streaming';
  const failed = message.status === 'failed';
  // v1.13.7: match the MessageList.flatten trim guard so a whitespace-only
  // assistant turn doesn't render an empty bubble + dangling ActionRow.
  const hasContent = message.content.trim().length > 0;
  // v1.8.2: if metadata stamps an error reason, surface it inline under the
  // generic "message failed" line. Keeps the user's eye where it already is
  // rather than introducing a separate banner.
  const errorMeta =
    message.metadata !== null && message.metadata.kind === 'error'
      ? message.metadata
      : null;

  return (
    <div className="group flex flex-col gap-2">
      {(hasContent || isStreaming) && (
        <SendToTerminalMenu>
          <div className="max-w-[90%] text-sm leading-relaxed space-y-2 break-words min-w-0">
            {hasContent ? <MarkdownRenderer content={message.content} /> : null}
            {isStreaming && (
              <span className="inline-block w-1.5 h-3.5 align-baseline bg-muted-foreground/60 animate-pulse" />
            )}
          </div>
        </SendToTerminalMenu>
      )}
      {failed && (
        <div className="text-xs text-destructive">
          message failed
          {errorMeta && (
            <span className="block text-muted-foreground mt-0.5">
              {ERROR_REASON_LABELS[errorMeta.error_reason]}
              {errorMeta.error_text ? ` — ${errorMeta.error_text}` : ''}
            </span>
          )}
        </div>
      )}
      {!isStreaming && <StatsLine message={message} />}
      {!isStreaming && hasContent && <ActionRow message={message} />}
    </div>
  );
}