import path from 'node:path';
import * as vscode from 'vscode';
import { isDecisionFile, parseDecision } from '../model/decisions';
import { isMainFile, isRegistryFile } from '../model/format';
import { DecisionPanel, decisionPanelFromIndex, decisionPanelStandalone } from '../model/panel';
import { ModelService } from '../model/service';
import { readText } from '../util/files';
import { log } from '../util/log';
import { sourceScriptUri } from '../webview/viewer3d';
import { SourceSession } from './sourceSession';
import { handleWebviewMessage, WebviewMessage } from '../webview/messages';
import { decisionPage, makeNonce } from '../webview/page';
import { DECISION_VIEW_TYPE, DIAGRAM_EDITOR_VIEW_TYPE, REGISTRY_VIEW_TYPE } from './viewTypes';

export { DECISION_VIEW_TYPE };

class DecisionView implements vscode.Disposable {
  private seq = 0;
  private timer: NodeJS.Timeout | undefined;
  private last: string | undefined;
  root: vscode.Uri | undefined;
  private readonly disposables: vscode.Disposable[] = [];
  /** The Source view; while it shows, a new page waits in `heldHtml`. */
  readonly source: SourceSession;
  private heldHtml: string | undefined;

  constructor(
    private readonly context: vscode.ExtensionContext,
    private readonly models: ModelService,
    readonly panel: vscode.WebviewPanel,
    readonly uri: vscode.Uri,
  ) {
    this.source = new SourceSession(context, panel, uri, 'decision', (shown) => {
      if (!shown && this.heldHtml !== undefined) {
        const html = this.heldHtml;
        this.heldHtml = undefined;
        this.panel.webview.html = html;
      }
    });
    this.disposables.push(
      this.source,
      panel.webview.onDidReceiveMessage((message: WebviewMessage) => {
        if (this.source.handle(message)) return;
        if (message.type === 'openDiagram') return void this.openInModel(message.path, DIAGRAM_EDITOR_VIEW_TYPE);
        if (message.type === 'openRegistry') return void this.openRegistryLine(message.file, message.line);
        if (message.type === 'openDecision') return void this.openInModel(message.file, DECISION_VIEW_TYPE);
        void handleWebviewMessage(message, this.uri, this.panel);
      }),
    );
    void this.update();
  }

  private async openInModel(relativePath: string, viewType: string): Promise<void> {
    if (!this.root) return;
    const target = vscode.Uri.joinPath(this.root, ...relativePath.split('/'));
    try {
      await vscode.workspace.fs.stat(target);
    } catch {
      vscode.window.showWarningMessage(`Archify: ${relativePath} does not exist in this model.`);
      return;
    }
    await vscode.commands.executeCommand('vscode.openWith', target, viewType, vscode.ViewColumn.Active);
  }

  private async openRegistryLine(file: string, line?: number): Promise<void> {
    if (!this.root) return;
    const target = vscode.Uri.joinPath(this.root, ...file.split('/'));
    const column = this.panel.viewColumn === vscode.ViewColumn.One ? vscode.ViewColumn.Two : vscode.ViewColumn.One;
    const at = Math.max(line ?? 0, 0);
    await vscode.window.showTextDocument(target, { viewColumn: column, selection: new vscode.Range(at, 0, at, 0) });
  }

  scheduleUpdate(): void {
    clearTimeout(this.timer);
    this.timer = setTimeout(() => void this.update(), 300);
  }

  async update(): Promise<void> {
    clearTimeout(this.timer);
    const seq = ++this.seq;
    let decision: DecisionPanel;
    try {
      this.root = await this.models.rootOf(this.uri);
      if (this.root) {
        const rel = path.relative(this.root.fsPath, this.uri.fsPath).split(path.sep).join('/');
        decision = decisionPanelFromIndex(await this.models.index(this.root), rel);
      } else {
        const name = path.basename(this.uri.path);
        decision = decisionPanelStandalone(name, parseDecision(await readText(this.uri), name));
      }
    } catch (error) {
      log().warn(`Decision view failed for ${this.uri.fsPath}: ${error instanceof Error ? error.message : String(error)}`);
      return;
    }
    if (seq !== this.seq) return;
    const fingerprint = JSON.stringify(decision);
    if (fingerprint === this.last) return;
    this.last = fingerprint;
    const html = decisionPage(
      { cspSource: this.panel.webview.cspSource, nonce: makeNonce(), source: { scriptUri: sourceScriptUri(this.panel.webview, this.context.extensionUri), left: 'View' } },
      decision,
    );
    if (this.source.shown) this.heldHtml = html;
    else this.panel.webview.html = html;
  }

  dispose(): void {
    clearTimeout(this.timer);
    for (const d of this.disposables.splice(0)) d.dispose();
  }
}

/** Custom editor for .archify-decision files: the decision as a page, with its elements and diagrams. */
export class DecisionViewProvider implements vscode.CustomTextEditorProvider, vscode.Disposable {
  private readonly views = new Set<DecisionView>();
  private active: DecisionView | undefined;
  private readonly disposables: vscode.Disposable[];

  constructor(
    private readonly context: vscode.ExtensionContext,
    private readonly models: ModelService,
  ) {
    this.disposables = [
      vscode.window.registerCustomEditorProvider(DECISION_VIEW_TYPE, this, {
        webviewOptions: { retainContextWhenHidden: true, enableFindWidget: true },
        supportsMultipleEditorsPerDocument: true,
      }),
      models.onDidChangeModel(({ root }) => {
        for (const view of this.views) if (view.root?.toString() === root.toString()) view.scheduleUpdate();
      }),
      vscode.workspace.onDidChangeTextDocument((event) => {
        if (!isDecisionFile(event.document.fileName) && !isRegistryFile(event.document.fileName) && !isMainFile(event.document.fileName)) return;
        for (const view of this.views) if (!view.root && view.uri.toString() === event.document.uri.toString()) view.scheduleUpdate();
      }),
    ];
  }

  /** File shown in the focused decision view, if any. */
  get activeUri(): vscode.Uri | undefined {
    return this.active?.uri;
  }

  /** The view of the focused page, if any. */
  get activeView(): { source: SourceSession } | undefined {
    return this.active;
  }

  // A text editor provider: the page edits the file's own TextDocument (in
  // its Source view), so dirty state, save and undo are VS Code's.
  async resolveCustomTextEditor(document: vscode.TextDocument, panel: vscode.WebviewPanel): Promise<void> {
    panel.webview.options = { enableScripts: true };
    const view = new DecisionView(this.context, this.models, panel, document.uri);
    this.views.add(view);
    const onViewState = () => {
      if (panel.active) this.active = view;
      else if (this.active === view) this.active = undefined;
      if (panel.active) void vscode.commands.executeCommand('setContext', 'archify.inModel', Boolean(view.root));
    };
    panel.onDidChangeViewState(onViewState);
    onViewState();
    panel.onDidDispose(() => {
      this.views.delete(view);
      if (this.active === view) this.active = undefined;
      view.dispose();
    });
  }

  dispose(): void {
    for (const view of this.views) view.dispose();
    this.views.clear();
    for (const d of this.disposables.splice(0)) d.dispose();
  }
}