"use client";

/**
 * T-172…T-175 (A-010) — the AI knowledge-assistant dialog.
 *
 * One thin view over the five assistant capabilities in `assistantApi`
 * (plain JSON one-shots — no SSE, no conversation panel; the server keeps
 * each call in a HIDDEN `assistant:*` conversation that never lists in the
 * panel). Mounted at the workspace shell (like the generate dialog) so the
 * command palette and the block context menu can open any mode.
 *
 * Mode inputs/outputs:
 *   - extract-actions   → notes textarea → real tasks (a success toast lists
 *                         them; EDIT-gated, 403 for GUEST)
 *   - generate-faqs     → the current page (context.pageId) → FAQ draft page
 *                         (navigates to it on success)
 *   - find-duplicates   → free-text query (optional) → link list of groups
 *   - find-stale        → days selector (90 default) → link list
 *   - suggest-metadata  → the current page (context.pageId) → Apply/Dismiss
 *                         (Apply = apply-metadata, the server re-checks that
 *                         each field exactly matches the stored suggestion)
 *
 * a11y mirrors the `DbAiDialog` chrome (role="dialog" aria-modal, focus trap,
 * Escape closes + aborts, focus restored, aria-live announces the state).
 *
 * Pinned testids (do not rename):
 *   assistant-dialog         the dialog (role=dialog)
 *   assistant-input          the mode input (textarea/select/button)
 *   assistant-run            the action button
 *   assistant-error-banner   the error banner (429/402/422/…)
 *   assistant-result         the result region (aria-live)
 *   assistant-apply          the suggest-metadata Apply button
 *   assistant-dismiss        the suggest-metadata Dismiss button
 */
import { useCallback, useEffect, useRef, useState } from "react";
import { useParams, useRouter } from "next/navigation";
import { AlertTriangle, Check, Loader2, RotateCcw, Sparkles, X } from "lucide-react";
import { useUiStore, toast, type AssistantMode } from "@/stores/ui-store";
import { useWorkspace } from "@/hooks/use-workspace";
import { isApiError, ApiError } from "@/lib/api";
import { assistantApi, type AssistantSuggestResult } from "@/lib/ai";
import { useQueryClient } from "@tanstack/react-query";
import { DbAiDialog } from "./db-ai-dialog";

const MODE_TITLES: Record<AssistantMode, string> = {
  "extract-actions": "Extract action items",
  "generate-faqs": "Generate FAQs",
  "find-duplicates": "Find duplicate pages",
  "find-stale": "Find stale pages",
  "suggest-metadata": "Suggest page metadata"
};

/** The error-banner text per failure class (the server's message is kept —
 *  the banner is the single error surface, like the generate dialog). */
function errorText(err: unknown): { message: string; retryable: boolean } {
  if (isApiError(err)) {
    if (err.status === 429) return { message: "Too many AI requests — slow down for a minute.", retryable: true };
    if (err.code === "AI_BUDGET_EXCEEDED" || err.status === 402)
      return { message: "Monthly AI token budget reached. Ask an admin.", retryable: false };
    if (err.status === 422)
      return { message: "The AI produced an invalid result — nothing was written. Try again.", retryable: true };
    if (err.status === 403) return { message: "You do not have permission for this action.", retryable: false };
    return { message: err.message || "Request failed.", retryable: true };
  }
  return { message: "Something went wrong.", retryable: true };
}

type ResultBody =
  | { kind: "tasks"; lines: string[] }
  | { kind: "links"; groups: Array<{ label: string; links: Array<{ id: string; title: string; hint?: string }> }> }
  | { kind: "suggestion"; data: AssistantSuggestResult };

export function AssistantDialog() {
  const open = useUiStore((s) => s.assistantOpen);
  const context = useUiStore((s) => s.assistantContext);
  const setOpen = useUiStore((s) => s.setAssistant);
  const slug = useParams<{ workspace: string }>()?.workspace ?? "default";
  const { data: workspace } = useWorkspace(slug);
  const router = useRouter();
  const queryClient = useQueryClient();

  const mode: AssistantMode | null = context?.mode ?? null;
  const pageId = context?.pageId;

  const [text, setText] = useState("");
  const [days, setDays] = useState(90);
  const [running, setRunning] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [retryable, setRetryable] = useState(false);
  const [result, setResult] = useState<ResultBody | null>(null);
  const abortRef = useRef<AbortController | null>(null);

  const close = useCallback(() => {
    abortRef.current?.abort();
    abortRef.current = null;
    setOpen(false, null);
    setRunning(false);
    setError(null);
    setResult(null);
    setText("");
    setDays(90);
  }, [setOpen]);

  const run = useCallback(async () => {
    if (!workspace?.id || !mode || running) return;
    setError(null);
    setResult(null);
    setRunning(true);
    const controller = new AbortController();
    abortRef.current = controller;
    const wsId = workspace.id;

    try {
      if (mode === "extract-actions") {
        const res = await assistantApi.extractActions(wsId, text.trim(), controller.signal);
        if (res.tasks.length === 0) {
          setResult({ kind: "tasks", lines: ["No action items found in the text."] });
        } else {
          setResult({
            kind: "tasks",
            lines: res.tasks.map((t) => `• ${t.title}${t.dueDate ? ` (due ${t.dueDate})` : ""}`)
          });
          toast("success", `Created ${res.tasks.length} task${res.tasks.length === 1 ? "" : "s"}`, "From the AI assistant");
        }
      } else if (mode === "generate-faqs") {
        if (!pageId) throw new ApiError("VALIDATION_ERROR", 400, "No page selected.");
        const res = await assistantApi.generateFaqs(wsId, [pageId], controller.signal);
        toast("success", `FAQ page created (${res.faqCount} question${res.faqCount === 1 ? "" : "s"})`, res.page.title);
        close();
        router.push(`/w/${slug}/page/${res.page.id}`);
        return;
      } else if (mode === "find-duplicates") {
        const res = await assistantApi.findDuplicates(wsId, { query: text.trim() || undefined }, controller.signal);
        setResult({
          kind: "links",
          groups: res.groups
            .filter((g) => g.pages.length >= 2)
            .map((g) => ({
              label: g.reason ? `${g.reason} (${Math.round(g.similarity * 100)}% similar)` : "Possible duplicates",
              links: g.pages.map((p) => ({ id: p.pageId, title: p.title, hint: p.updatedAt.slice(0, 10) }))
            }))
        });
        if (res.groups.length === 0) setResult({ kind: "links", groups: [] });
      } else if (mode === "find-stale") {
        const res = await assistantApi.findStale(wsId, { days }, controller.signal);
        setResult({
          kind: "links",
          groups: res.pages.length
            ? [
                {
                  label: `Not updated in ${days}+ days`,
                  links: res.pages.map((p) => ({ id: p.pageId, title: p.title, hint: p.reason }))
                }
              ]
            : []
        });
      } else {
        // suggest-metadata
        if (!pageId) throw new ApiError("VALIDATION_ERROR", 400, "No page selected.");
        const res = await assistantApi.suggestMetadata(wsId, pageId, controller.signal);
        setResult({ kind: "suggestion", data: res });
      }
    } catch (e) {
      if (e instanceof DOMException && e.name === "AbortError") return;
      const { message, retryable: canRetry } = errorText(e);
      setError(message);
      setRetryable(canRetry);
    } finally {
      setRunning(false);
      abortRef.current = null;
    }
  }, [workspace, mode, running, text, days, pageId, slug, router, close]);

  const applySuggestion = useCallback(
    async (suggestionId: string, fields: { title?: string; description?: string }) => {
      if (!workspace?.id || running) return;
      setRunning(true);
      setError(null);
      try {
        await assistantApi.applyMetadata(workspace.id, suggestionId, fields);
        // Refresh the page data the suggestion changed (title/description).
        await queryClient.invalidateQueries({ queryKey: ["pages", pageId] });
        queryClient.invalidateQueries({ queryKey: ["workspaces", workspace.id, "page-tree"] });
        toast("success", "Metadata applied", "Title and/or description updated");
        close();
      } catch (e) {
        if (e instanceof DOMException && e.name === "AbortError") return;
        setError(errorText(e).message);
        setRetryable(false);
      } finally {
        setRunning(false);
      }
    },
    [workspace, running, pageId, queryClient, close]
  );

  const canRun =
    !running &&
    (mode === "extract-actions" ? text.trim().length > 0 : mode === "find-stale" || mode === "find-duplicates" ? true : !!pageId);

  const live = running
    ? `Running ${mode ? MODE_TITLES[mode] : ""}…`
    : error
      ? `Error: ${error}`
      : result
        ? "Result ready."
        : "Describe or select to run.";

  const placeholder =
    mode === "extract-actions"
      ? "Paste notes, a transcript, or a chat thread…\n\n- Ship the whiteboard export\n- Review the Q3 budget"
    : mode === "find-duplicates"
      ? "Optional: narrow the search (e.g. \"pricing\")"
      : mode === "find-stale"
        ? "Pages not updated in the selected number of days will be listed."
        : mode === "generate-faqs"
          ? "FAQs will be generated from this page's content into a new draft page."
          : "A suggested title/description will be shown for review before anything is applied.";

  return (
    <DbAiDialog
      open={open && mode !== null}
      title={mode ? MODE_TITLES[mode] : "AI assistant"}
      testId="assistant-dialog"
      onClose={close}
      loadingText="Working…"
      live={live}
      footer={
        <div className="flex w-full items-center justify-end gap-2">
          {result && result.kind === "suggestion" ? (
            <>
              <button
                type="button"
                data-testid="assistant-dismiss"
                onClick={close}
                className="rounded-md border border-border px-3 py-1.5 text-sm hover:bg-accent"
              >
                Dismiss
              </button>
              <button
                type="button"
                data-testid="assistant-apply"
                disabled={running}
                onClick={() =>
                  void applySuggestion(result.data.suggestionId, {
                    ...(result.data.suggested.title !== undefined ? { title: result.data.suggested.title } : {}),
                    ...(result.data.suggested.description !== undefined ? { description: result.data.suggested.description } : {})
                  })
                }
                className="inline-flex items-center gap-1.5 rounded-md bg-primary px-3 py-1.5 text-sm text-primary-foreground hover:opacity-90 disabled:opacity-50"
              >
                <Check className="size-4" aria-hidden />
                Apply
              </button>
            </>
          ) : (
            <>
              <button
                type="button"
                onClick={close}
                className="rounded-md border border-border px-3 py-1.5 text-sm hover:bg-accent"
              >
                Close
              </button>
              {error && retryable ? (
                <button
                  type="button"
                  onClick={() => void run()}
                  className="inline-flex items-center gap-1.5 rounded-md border border-border px-3 py-1.5 text-sm hover:bg-accent"
                >
                  <RotateCcw className="size-4" aria-hidden />
                  Retry
                </button>
              ) : null}
              <button
                type="button"
                data-testid="assistant-run"
                disabled={!canRun}
                onClick={() => void run()}
                className="inline-flex items-center gap-1.5 rounded-md bg-primary px-3 py-1.5 text-sm text-primary-foreground hover:opacity-90 disabled:opacity-50"
              >
                {running ? <Loader2 className="size-4 animate-spin" aria-hidden /> : <Sparkles className="size-4" aria-hidden />}
                Run
              </button>
            </>
          )}
        </div>
      }
    >
      {/* The mode input (textarea / select / notice). */}
      {mode === "extract-actions" || mode === "find-duplicates" ? (
        <textarea
          data-testid="assistant-input"
          value={text}
          onChange={(e) => setText(e.target.value)}
          rows={mode === "extract-actions" ? 8 : 3}
          placeholder={placeholder}
          className="w-full rounded-md border border-border bg-background p-2.5 text-sm outline-none placeholder:text-muted-foreground focus:ring-1 focus:ring-ring"
          aria-label={placeholder}
        />
      ) : null}

      {mode === "find-stale" ? (
        <div className="flex items-center gap-2" data-testid="assistant-input">
          <label htmlFor="assistant-stale-days" className="text-sm text-muted-foreground">
            Not updated in
          </label>
          <select
            id="assistant-stale-days"
            value={days}
            onChange={(e) => setDays(Number(e.target.value))}
            className="h-8 rounded-md border border-border bg-background px-2 text-sm"
          >
            <option value={30}>30 days</option>
            <option value={90}>90 days</option>
            <option value={180}>180 days</option>
            <option value={365}>365 days</option>
          </select>
        </div>
      ) : null}

      {mode === "generate-faqs" || mode === "suggest-metadata" ? (
        <p className="text-sm text-muted-foreground" data-testid="assistant-input">
          {placeholder}
        </p>
      ) : null}

      {/* The error banner (the single error surface — 429/402/422/403). */}
      {error ? (
        <div
          data-testid="assistant-error-banner"
          role="alert"
          className="flex items-start gap-2 rounded-md border border-red-300 bg-red-50 p-2.5 text-sm text-red-800 dark:border-red-900 dark:bg-red-950/40 dark:text-red-300"
        >
          <AlertTriangle className="mt-0.5 size-4 shrink-0" aria-hidden />
          <span>{error}</span>
        </div>
      ) : null}

      {/* The result region. */}
      {result ? (
        <div data-testid="assistant-result" className="text-sm">
          {result.kind === "tasks" ? (
            <ul className="space-y-1">
              {result.lines.map((l) => (
                <li key={l} className="flex items-start gap-2">
                  <Check className="mt-0.5 size-4 shrink-0 text-emerald-600 dark:text-emerald-400" aria-hidden />
                  <span>{l}</span>
                </li>
              ))}
            </ul>
          ) : null}

          {result.kind === "links" ? (
            result.groups.length === 0 ? (
              <p className="rounded-md border border-border bg-background/60 p-3 text-muted-foreground">
                Nothing found — the workspace looks clean.
              </p>
            ) : (
              <div className="space-y-3">
                {result.groups.map((g) => (
                  <div key={g.label}>
                    <p className="mb-1 text-xs font-medium text-muted-foreground">{g.label}</p>
                    <ul className="space-y-0.5">
                      {g.links.map((l) => (
                        <li key={l.id}>
                          <button
                            type="button"
                            onClick={() => {
                              close();
                              router.push(`/w/${slug}/page/${l.id}`);
                            }}
                            className="flex w-full items-center gap-2 rounded px-1.5 py-1 text-left hover:bg-accent"
                          >
                            <span className="min-w-0 flex-1 truncate">{l.title || "Untitled"}</span>
                            {l.hint ? <span className="shrink-0 text-xs text-muted-foreground">{l.hint}</span> : null}
                          </button>
                        </li>
                      ))}
                    </ul>
                  </div>
                ))}
              </div>
            )
          ) : null}

          {result.kind === "suggestion" ? (
            <div className="space-y-2 rounded-md border border-border bg-background/60 p-3">
              {result.data.suggested.title !== undefined ? (
                <div>
                  <p className="text-xs font-medium text-muted-foreground">Title</p>
                  <p className="text-foreground">{result.data.suggested.title}</p>
                </div>
              ) : null}
              {result.data.suggested.description !== undefined ? (
                <div>
                  <p className="text-xs font-medium text-muted-foreground">Description</p>
                  <p className="text-foreground">{result.data.suggested.description}</p>
                </div>
              ) : null}
              <p className="text-xs text-muted-foreground">Apply writes these via the normal page update (you keep review control).</p>
            </div>
          ) : null}
        </div>
      ) : null}
    </DbAiDialog>
  );
}