/** Accessible HUX-04 artifact UI. This module never fetches or executes content. */

import {
  Code2,
  Download,
  FileText,
  GitCompare,
  History,
  Image as ImageIcon,
  Pencil,
  Share2,
  Sparkles,
} from "lucide-react";
import { useMemo, useState } from "react";

import { artifactsEnabled, normalizeArtifactWorkspace, normalizePreview } from "./model.ts";
import type {
  Artifact,
  ArtifactAuthorization,
  ArtifactMutationIntent,
  ArtifactPreview,
  ArtifactScope,
  DiffIntent,
  HuxIdentity,
  PromoteIntent,
  RawArtifactEnvelope,
  RawPreviewPayload,
} from "./types.ts";

interface ArtifactWorkspaceProps {
  flags?: Iterable<string>;
  identity: HuxIdentity;
  scope: ArtifactScope;
  page: RawArtifactEnvelope;
  previews?: readonly RawPreviewPayload[];
  busy?: boolean;
  error?: string | null;
  onLoadPreview?: (intent: ArtifactMutationIntent & {version: number}) => void;
  onContinueEdit?: (intent: ArtifactMutationIntent) => void;
  onDiff?: (intent: DiffIntent) => void;
  onAuthorize?: (action: "download" | "share", intent: ArtifactMutationIntent) => void;
  onDownload?: (intent: ArtifactMutationIntent & {version: number}) => void;
  onShare?: (intent: ArtifactMutationIntent & {version: number}) => void;
  onPromote?: (intent: PromoteIntent) => void;
}

function intent(artifact: Artifact, scope: ArtifactScope): ArtifactMutationIntent {
  return {artifactId: artifact.id, expectedVersion: artifact.currentVersion, scope};
}

function RendererIcon({artifact}: {artifact: Artifact}) {
  if (artifact.renderer === "image") return <ImageIcon aria-hidden />;
  if (artifact.renderer === "code" || artifact.renderer === "data") return <Code2 aria-hidden />;
  return <FileText aria-hidden />;
}

function Preview({artifact, preview}: {artifact: Artifact; preview: ArtifactPreview | null}) {
  if (!preview) return <div className="hux-artifact-preview-empty">
    <RendererIcon artifact={artifact} />
    <p>Preview not loaded. Content stays behind its verified content reference.</p>
  </div>;
  if (preview.renderer === "image") {
    return <figure className="hux-artifact-image">
      <img src={preview.blobUrl!} alt={`Preview of ${artifact.title}`} />
      <figcaption>{preview.mime}; local authorized preview</figcaption>
    </figure>;
  }
  if (preview.renderer === "audio") {
    return <div className="hux-artifact-audio">
      <audio src={preview.blobUrl!} controls preload="metadata">
        Audio preview is unavailable in this browser.
      </audio>
      <span>{preview.mime}; local authorized preview</span>
    </div>;
  }
  const className = `hux-artifact-${preview.renderer}`;
  return <div className={className} aria-label={`${preview.renderer} preview`}>
    {preview.renderer === "report" && <h3>Report preview</h3>}
    <pre tabIndex={0}><code>{preview.text}</code></pre>
  </div>;
}

function AuthorizationAction({action, state, busy, onAuthorize, onAction}: {
  action: "download" | "share";
  state: ArtifactAuthorization["download"];
  busy: boolean;
  onAuthorize: () => void;
  onAction: () => void;
}) {
  const label = action === "download" ? "Download" : "Share";
  const Icon = action === "download" ? Download : Share2;
  if (state === "authorized") return <button type="button" disabled={busy} onClick={onAction}>
    <Icon aria-hidden /> {label}
  </button>;
  if (state === "requires_approval") return <button type="button" disabled={busy} onClick={onAuthorize}>
    <Icon aria-hidden /> Request {label.toLowerCase()} approval
  </button>;
  return <button type="button" disabled aria-label={`${label} unavailable`}>
    <Icon aria-hidden /> {label} unavailable
  </button>;
}

function VersionHistory({artifact, selectedVersion, setSelectedVersion, busy, scope, onDiff}: {
  artifact: Artifact;
  selectedVersion: number;
  setSelectedVersion: (version: number) => void;
  busy: boolean;
  scope: ArtifactScope;
  onDiff?: ArtifactWorkspaceProps["onDiff"];
}) {
  return <section className="hux-artifact-history" aria-labelledby="hux-artifact-history-title">
    <h3 id="hux-artifact-history-title"><History aria-hidden /> Immutable version history</h3>
    <ol>{[...artifact.versions].reverse().map((version) => <li key={version.version}
      data-current={version.version === artifact.currentVersion}>
      <button type="button" aria-pressed={selectedVersion === version.version}
        onClick={() => setSelectedVersion(version.version)}>
        <strong>Version {version.version}</strong>
        <span>{version.note || `Created by ${version.createdBy}`}</span>
        <time dateTime={version.createdAt}>{new Date(version.createdAt).toLocaleString()}</time>
      </button>
      {version.version > 1 && onDiff && <button className="hux-artifact-diff" type="button"
        disabled={busy} onClick={() => onDiff({
          ...intent(artifact, scope), fromVersion: version.diffFrom || version.version - 1,
          toVersion: version.version,
        })} aria-label={`Compare version ${version.version}`}><GitCompare aria-hidden /> Compare</button>}
    </li>)}</ol>
  </section>;
}

/** Render nothing unless all negotiated HUX-04 dependencies are active. */
export function ArtifactWorkspace(props: ArtifactWorkspaceProps) {
  const enabled = artifactsEnabled(props.flags);
  const page = useMemo(() => enabled ?
    normalizeArtifactWorkspace(props.page, props.identity, props.scope) : null,
  [enabled, props.identity, props.page, props.scope]);
  const [selectedId, setSelectedId] = useState<string | null>(null);
  const [selectedVersion, setSelectedVersion] = useState<number | null>(null);
  if (!enabled || !page) return null;
  const artifact = page.artifacts.find((item) => item.id === selectedId) || page.artifacts[0] || null;
  const version = artifact ? Math.min(selectedVersion || artifact.currentVersion, artifact.currentVersion) : null;
  const rawPreview = artifact && version ? props.previews?.find((item) =>
    item.artifact_id === artifact.id && item.version === version) : undefined;
  const preview = artifact && rawPreview ?
    normalizePreview(rawPreview, artifact, props.identity, props.scope) : null;
  const attachments = artifact ? page.attachments.find((item) => item.artifactId === artifact.id) : null;
  const authorization = artifact ? page.authorizations.find((item) => item.artifactId === artifact.id) : null;

  function selectArtifact(item: Artifact) {
    setSelectedId(item.id);
    setSelectedVersion(item.currentVersion);
    props.onLoadPreview?.({...intent(item, props.scope), version: item.currentVersion});
  }

  function selectVersion(next: number) {
    if (!artifact) return;
    setSelectedVersion(next);
    props.onLoadPreview?.({...intent(artifact, props.scope), version: next});
  }

  return <section className="hux-artifacts" aria-label="Artifact workspace" aria-busy={props.busy}>
    <nav className="hux-artifact-list" aria-label="Artifacts">
      <header><h2><Sparkles aria-hidden /> Artifacts</h2>
        <p>Durable outputs from this conversation.</p></header>
      <ul>{page.artifacts.map((item) => <li key={item.id}>
        <button type="button" aria-current={artifact?.id === item.id ? "page" : undefined}
          onClick={() => selectArtifact(item)}>
          <RendererIcon artifact={item} />
          <span><strong>{item.title}</strong><small>{item.renderer} · v{item.currentVersion}</small></span>
        </button>
      </li>)}</ul>
      {!page.artifacts.length && <p className="hux-artifact-empty">No artifacts are attached.</p>}
    </nav>

    <main className="hux-artifact-main">
      {props.error && <p className="hux-artifact-error" role="alert">{props.error}</p>}
      {page.rejected > 0 && <p className="hux-artifact-warning" role="status">
        Some artifacts were withheld because their owner or workspace binding was invalid.
      </p>}
      {artifact && version ? <>
        <header className="hux-artifact-heading">
          <div><span>{artifact.renderer}</span><h2>{artifact.title}</h2>
            <p>Version {version} · {artifact.sensitivity} · {artifact.language || artifact.type}</p></div>
          <div className="hux-artifact-actions">
            <button type="button" disabled={props.busy}
              onClick={() => props.onContinueEdit?.(intent(artifact, props.scope))}>
              <Pencil aria-hidden /> Continue editing
            </button>
            <AuthorizationAction action="download" state={authorization?.download || "unavailable"}
              busy={Boolean(props.busy)}
              onAuthorize={() => props.onAuthorize?.("download", intent(artifact, props.scope))}
              onAction={() => props.onDownload?.({...intent(artifact, props.scope), version})} />
            <AuthorizationAction action="share" state={authorization?.share || "unavailable"}
              busy={Boolean(props.busy)}
              onAuthorize={() => props.onAuthorize?.("share", intent(artifact, props.scope))}
              onAction={() => props.onShare?.({...intent(artifact, props.scope), version})} />
          </div>
        </header>
        <Preview artifact={artifact} preview={preview} />
        <section className="hux-artifact-evidence" aria-label="Attached research evidence">
          <div><strong>{attachments?.sourceCount || 0}</strong><span>Sources attached</span></div>
          <div><strong>{attachments?.citationCount || 0}</strong><span>Citations attached</span></div>
        </section>
        <button className="hux-artifact-promote" type="button" disabled={props.busy ||
          artifact.promotedVersion === version} onClick={() => props.onPromote?.({
            ...intent(artifact, props.scope), targetProjectId: props.scope.projectId, version,
          })}>
          {artifact.promotedVersion === version ? "Promoted to this project" : "Promote version to project"}
        </button>
      </> : <p className="hux-artifact-empty">Select an artifact to inspect it.</p>}
    </main>

    <aside className="hux-artifact-side" aria-label="Artifact versions">
      {artifact && version ? <VersionHistory artifact={artifact} selectedVersion={version}
        setSelectedVersion={selectVersion} busy={Boolean(props.busy)} scope={props.scope}
        onDiff={props.onDiff} /> : <p>Version history will appear here.</p>}
    </aside>
    <p className="sr-only" role="status" aria-live="polite">
      {props.busy ? "Artifact workspace is updating" : `${page.artifacts.length} artifacts available`}
    </p>
  </section>;
}