// One Oxygen repository as VS Code sees it: the source control provider,

// its resource groups, the status bar item, and the watchers that keep

// them fresh (spec §3, §5.1, §5.4).

import * as vscode from "vscode";

import { basename, join, relative } from "node:path";

import { Oxy, PathStatus, StatusInfo } from "./oxy";

import { baseUri } from "./contentProvider";

const STATUS_LETTER: Record<PathStatus, string> = {

  Added: "A",

  Modified: "M",

  Removed: "D",

  Renamed: "R",

  ModeChanged: "X",

  ConflictEdited: "‼",

  Resolved: "✔",

};

const STATUS_WORD: Record<PathStatus, string> = {

  Added: "added",

  Modified: "modified",

  Removed: "removed",

  Renamed: "renamed",

  ModeChanged: "mode changed",

  ConflictEdited: "conflict markers remain",

  Resolved: "conflict resolved",

};

const STATUS_COLOR: Record<PathStatus, string> = {

  Added: "gitDecoration.addedResourceForeground",

  Modified: "gitDecoration.modifiedResourceForeground",

  Removed: "gitDecoration.deletedResourceForeground",

  Renamed: "gitDecoration.renamedResourceForeground",

  ModeChanged: "gitDecoration.modifiedResourceForeground",

  ConflictEdited: "gitDecoration.conflictingResourceForeground",

  Resolved: "gitDecoration.stageModifiedResourceForeground",

};

export class OxyResourceState implements vscode.SourceControlResourceState {

  readonly resourceUri: vscode.Uri;

  readonly decorations: vscode.SourceControlResourceDecorations;

  readonly command: vscode.Command;

  constructor(

    readonly repository: Repository,

    readonly path: string,

    readonly status: PathStatus,

  ) {

    this.resourceUri = vscode.Uri.file(join(repository.root, path));

    this.decorations = {

      strikeThrough: status === "Removed",

      tooltip: STATUS_WORD[status],

      faded: false,

    };

    this.command = { command: "oxygen.openChanges", title: "Open Changes", arguments: [this] };

  }

  get letter(): string {

    return STATUS_LETTER[this.status];

  }

  get color(): vscode.ThemeColor {

    return new vscode.ThemeColor(STATUS_COLOR[this.status]);

  }

}

export class Repository implements vscode.Disposable, vscode.QuickDiffProvider {

  readonly sourceControl: vscode.SourceControl;

  readonly conflictsGroup: vscode.SourceControlResourceGroup;

  readonly changesGroup: vscode.SourceControlResourceGroup;

  private readonly statusBar: vscode.StatusBarItem;

  private readonly disposables: vscode.Disposable[] = [];

  private readonly onDidChangeStatusEmitter = new vscode.EventEmitter<StatusInfo>();

  readonly onDidChangeStatus = this.onDidChangeStatusEmitter.event;

  private latest: StatusInfo | undefined;

  private refreshTimer: NodeJS.Timeout | undefined;

  private refreshing: Promise<void> | undefined;

  private refreshAgain = false;

  constructor(

    readonly oxy: Oxy,

    readonly root: string,

    readonly workspaceFolder: vscode.WorkspaceFolder | undefined,

  ) {

    const rootUri = vscode.Uri.file(root);

    this.sourceControl = vscode.scm.createSourceControl("oxygen", `Oxygen (${basename(root)})`, rootUri);

    this.sourceControl.quickDiffProvider = this;

    this.sourceControl.acceptInputCommand = { command: "oxygen.commit", title: "Commit", arguments: [this] };

    this.sourceControl.inputBox.placeholder = "Message (Ctrl+Enter to commit)";

    this.conflictsGroup = this.sourceControl.createResourceGroup("conflicts", "Conflicts");

    this.conflictsGroup.hideWhenEmpty = true;

    this.changesGroup = this.sourceControl.createResourceGroup("changes", "Changes");

    this.statusBar = vscode.window.createStatusBarItem("oxygen.status", vscode.StatusBarAlignment.Left, 100);

    this.statusBar.name = "Oxygen";

    this.statusBar.command = "oxygen.showLog";

    this.disposables.push(this.sourceControl, this.conflictsGroup, this.changesGroup, this.statusBar, this.onDidChangeStatusEmitter);

    if (vscode.workspace.getConfiguration("oxygen").get<boolean>("autoRefresh", true)) {

      // Files in the workspace, except the repository's own store.

      const files = vscode.workspace.createFileSystemWatcher(new vscode.RelativePattern(rootUri, "**/*"));

      const onFile = (uri: vscode.Uri) => {

        if (!uri.fsPath.startsWith(join(root, ".oxy"))) {

          this.scheduleRefresh();

        }

      };

      files.onDidChange(onFile, this, this.disposables);

      files.onDidCreate(onFile, this, this.disposables);

      files.onDidDelete(onFile, this, this.disposables);

      this.disposables.push(files);

      // Any operation, including ones run from a terminal, moves the op head.

      const ops = vscode.workspace.createFileSystemWatcher(new vscode.RelativePattern(rootUri, ".oxy/ops/head"));

      ops.onDidChange(() => this.scheduleRefresh(), this, this.disposables);

      ops.onDidCreate(() => this.scheduleRefresh(), this, this.disposables);

      this.disposables.push(ops);

    }

    vscode.window.onDidChangeWindowState((s) => s.focused && this.scheduleRefresh(), this, this.disposables);

  }

  get status(): StatusInfo | undefined {

    return this.latest;

  }

  /** The repository-relative path of a file under this root, or undefined. */

  relativePath(uri: vscode.Uri): string | undefined {

    if (uri.scheme !== "file") {

      return undefined;

    }

    const rel = relative(this.root, uri.fsPath);

    if (!rel || rel.startsWith("..") || rel.startsWith(".oxy")) {

      return undefined;

    }

    return rel.split("\\").join("/");

  }

  scheduleRefresh(): void {

    if (this.refreshTimer) {

      clearTimeout(this.refreshTimer);

    }

    this.refreshTimer = setTimeout(() => void this.refresh(), 250);

  }

  /** Refresh now; a refresh requested during one runs once more afterwards. */

  refresh(): Promise<void> {

    if (this.refreshing) {

      this.refreshAgain = true;

      return this.refreshing;

    }

    this.refreshing = this.doRefresh().finally(() => {

      this.refreshing = undefined;

      if (this.refreshAgain) {

        this.refreshAgain = false;

        void this.refresh();

      }

    });

    return this.refreshing;

  }

  private async doRefresh(): Promise<void> {

    try {

      const [status, prompt] = await Promise.all([this.oxy.status(this.root), this.oxy.prompt(this.root)]);

      this.latest = status;

      const conflicted = new Set(status.conflicts.map((c) => c.path).filter((p): p is string => !!p));

      const conflicts: OxyResourceState[] = [];

      const changes: OxyResourceState[] = [];

      for (const p of status.paths) {

        const state = new OxyResourceState(this, p.path, p.status);

        if (p.status === "ConflictEdited" || p.status === "Resolved" || conflicted.has(p.path)) {

          conflicts.push(state);

        } else {

          changes.push(state);

        }

      }

      // Conflicted files the working copy has not touched yet still need resolving.

      for (const c of status.conflicts) {

        if (c.path && !status.paths.some((p) => p.path === c.path)) {

          conflicts.push(new OxyResourceState(this, c.path, "ConflictEdited"));

        }

      }

      this.conflictsGroup.resourceStates = conflicts;

      this.changesGroup.resourceStates = changes;

      this.sourceControl.count = status.paths.length + (status.conflicts.length ? status.conflicts.length : 0);

      this.updateStatusBar(status, prompt);

      this.onDidChangeStatusEmitter.fire(status);

    } catch (e) {

      this.statusBar.text = "$(warning) oxy";

      this.statusBar.tooltip = String(e);

      this.statusBar.show();

    }

  }

  private updateStatusBar(status: StatusInfo, prompt: string): void {

    if (!vscode.workspace.getConfiguration("oxygen").get<boolean>("statusBar.enabled", true)) {

      this.statusBar.hide();

      return;

    }

    const text = prompt || `${status.bookmark} ${status.working_copy.slice(0, 8)}`;

    this.statusBar.text = text;

    this.statusBar.tooltip = new vscode.MarkdownString(

      `**Oxygen** ${basename(this.root)}\n\n` +

        `Bookmark \`${status.bookmark}\` with ${status.heads} head${status.heads === 1 ? "" : "s"}\n\n` +

        (status.conflicted ? `$(warning) The state has conflicts\n\n` : "") +

        `${status.paths.length} changed path${status.paths.length === 1 ? "" : "s"}`,

      true,

    );

    this.statusBar.backgroundColor = status.conflicted ? new vscode.ThemeColor("statusBarItem.errorBackground") : undefined;

    this.statusBar.show();

  }

  // QuickDiffProvider: the base version of a file, served from oxy.

  provideOriginalResource(uri: vscode.Uri): vscode.Uri | undefined {

    const rel = this.relativePath(uri);

    if (!rel) {

      return undefined;

    }

    const status = this.latest?.paths.find((p) => p.path === rel)?.status;

    if (status === "Added") {

      return undefined;

    }

    return baseUri(this.root, rel);

  }

  dispose(): void {

    if (this.refreshTimer) {

      clearTimeout(this.refreshTimer);

    }

    for (const d of this.disposables) {

      d.dispose();

    }

  }

}