import { ContainerModule } from '@theia/core/shared/inversify';
import { inject, injectable } from '@theia/core/shared/inversify';
import {
  Command, CommandContribution, CommandRegistry, MenuContribution,
  MenuModelRegistry, MessageService,
} from '@theia/core/lib/common';
import { WidgetFactory, bindViewContribution, FrontendApplicationContribution } from '@theia/core/lib/browser';
import { QuickInputService } from '@theia/core/lib/common/quick-pick-service';
import { StorageService } from '@theia/core/lib/browser/storage-service';
import { BinaryBuffer } from '@theia/core/lib/common/buffer';
import { FileService } from '@theia/filesystem/lib/browser/file-service';
import { WorkspaceService } from '@theia/workspace/lib/browser/workspace-service';
import { WorkspaceCommands } from '@theia/workspace/lib/browser/workspace-commands';
import { EditorManager } from '@theia/editor/lib/browser/editor-manager';
import URI from '@theia/core/lib/common/uri';
import {
  ProjectTemplate, TEMPLATES, declaredSourceDirs, isValidModuleName,
  isValidProjectName, moduleNameOf, renderDefModule, renderImplModule,
  scaffoldFiles, validateProjectFile,
} from './modula2-project';
import {
  MODULA2_EXPLORER_ID, Modula2ExplorerCommands, Modula2ExplorerContainerFactory,
  Modula2ExplorerContribution, Modula2ExplorerMenus, createModula2ExplorerWidget,
} from './modula2-explorer-widget';

const CATEGORY = 'Modula-2';

const Commands = {
  newModule: Command.toLocalizedCommand({ id: 'modula2.newModule', label: 'New Module...', category: CATEGORY }),
  newDefModule: Command.toLocalizedCommand({ id: 'modula2.newDefModule', label: 'New Definition Module...', category: CATEGORY }),
  newProject: Command.toLocalizedCommand({ id: 'modula2.newProject', label: 'New Modula-2 Project...', category: CATEGORY }),
  openProject: Command.toLocalizedCommand({ id: 'modula2.openProject', label: 'Open Project...', category: CATEGORY }),
  switchProject: Command.toLocalizedCommand({ id: 'modula2.switchProject', label: 'Switch Project...', category: CATEGORY }),
  closeProject: Command.toLocalizedCommand({ id: 'modula2.closeProject', label: 'Close Project', category: CATEGORY }),
  validate: Command.toLocalizedCommand({ id: 'modula2.validateProject', label: 'Validate Project', category: CATEGORY }),
};

@injectable()
class ProjectCommands implements CommandContribution {
  @inject(FileService) protected readonly files: FileService;
  @inject(WorkspaceService) protected readonly workspace: WorkspaceService;
  @inject(EditorManager) protected readonly editors: EditorManager;
  @inject(MessageService) protected readonly messages: MessageService;
  @inject(QuickInputService) protected readonly quickInput: QuickInputService;
  @inject(CommandRegistry) protected readonly commands: CommandRegistry;
  @inject(StorageService) protected readonly storage: StorageService;

  registerCommands(commands: CommandRegistry): void {
    commands.registerCommand(Commands.newModule, { execute: () => this.newModule(false) });
    commands.registerCommand(Commands.newDefModule, { execute: () => this.newModule(true) });
    commands.registerCommand(Commands.newProject, { execute: () => this.newProject() });
    commands.registerCommand(Commands.openProject, { execute: () => this.openProject() });
    commands.registerCommand(Commands.switchProject, { execute: () => this.switchProject() });
    commands.registerCommand(Commands.closeProject, { execute: () => this.closeProject() });
    commands.registerCommand(Commands.validate, { execute: () => this.validateProject() });
  }

  protected async root(): Promise<URI | undefined> {
    const roots = await this.workspace.roots;
    if (roots.length === 0) {
      this.messages.warn('Modula-2: open a folder first (File > Open Folder).');
      return undefined;
    }
    return roots[0].resource;
  }

  /** Candidate source directories: declared ones that exist, then src/, then the root. */
  protected async sourceDirChoices(root: URI): Promise<string[]> {
    const declared: string[] = [];
    try {
      const content = await this.files.read(root.resolve('modula2.json'));
      declared.push(...declaredSourceDirs(content.value));
    } catch {
      // No project file: fall through to conventions.
    }
    const out: string[] = [];
    for (const d of [...declared, 'src']) {
      if (d === '.' || d === '') continue;
      try {
        if (await this.files.exists(root.resolve(d))) out.push(d);
      } catch { /* ignore */ }
    }
    out.push('.');
    return [...new Set(out)];
  }

  protected async askModuleName(): Promise<string | undefined> {
    return this.quickInput.input({
      prompt: 'Module name (a Modula-2 identifier, e.g. MyModule)',
      placeHolder: 'MyModule',
      validateInput: async value => isValidModuleName(value.trim()) ?? null,
    });
  }

  protected async newModule(defOnly: boolean): Promise<void> {
    const root = await this.root();
    if (!root) return;
    const raw = await this.askModuleName();
    if (raw === undefined) return;
    const name = raw.trim();
    let makeDef = defOnly;
    let makeMod = !defOnly;
    if (!defOnly) {
      const kind = await this.quickInput.showQuickPick(
        [{ label: 'Implementation + definition', description: 'MyModule.mod and MyModule.def', value: 'both' },
         { label: 'Implementation only', description: 'MyModule.mod', value: 'mod' },
         { label: 'Definition only', description: 'MyModule.def', value: 'def' }],
        { placeholder: 'What to create?' },
      );
      if (!kind) return;
      makeDef = kind.value !== 'mod';
      makeMod = kind.value !== 'def';
    }
    const choices = await this.sourceDirChoices(root);
    let dir = choices[0];
    if (choices.length > 1) {
      const picked = await this.quickInput.showQuickPick(
        choices.map(c => ({ label: c === '.' ? '(project root)' : c, value: c })),
        { placeholder: 'Where to create the module?' },
      );
      if (!picked) return;
      dir = picked.value;
    }
    const created: string[] = [];
    const write = async (file: string, content: string): Promise<boolean> => {
      const uri = dir === '.' ? root.resolve(file) : root.resolve(`${dir}/${file}`);
      try {
        if (await this.files.exists(uri)) {
          this.messages.warn(`Modula-2: ${file} already exists, skipped.`);
          return false;
        }
        await this.files.writeFile(uri, BinaryBuffer.fromString(content));
        created.push(file);
        return true;
      } catch (error) {
        this.messages.error(`Modula-2: cannot write ${file}: ${error instanceof Error ? error.message : String(error)}`);
        return false;
      }
    };
    if (makeMod) await write(`${name}.mod`, renderImplModule(name));
    if (makeDef) await write(`${name}.def`, renderDefModule(name));
    if (created.length === 0) return;
    this.messages.info(`Modula-2: created ${created.join(', ')}.`);
    const first = dir === '.' ? root.resolve(created[0]) : root.resolve(`${dir}/${created[0]}`);
    try {
      await this.editors.open(first, { mode: 'activate' });
    } catch { /* created is enough */ }
  }

  protected async newProject(): Promise<void> {
    const root = await this.root();
    if (!root) return;
    const rawName = await this.quickInput.input({
      prompt: 'Project name (used for the folder and modula2.json)',
      placeHolder: 'HelloWorld',
      validateInput: async value => isValidProjectName(value.trim()) ?? null,
    });
    if (rawName === undefined) return;
    const name = rawName.trim();
    const template = await this.quickInput.showQuickPick(
      TEMPLATES.map(t => ({ label: t.label, description: t.description, value: t.id as ProjectTemplate })),
      { placeholder: 'Project template' },
    );
    if (!template) return;
    // Scaffold at the root when it is empty, else in a subfolder.
    let target = root;
    try {
      const stat = await this.files.resolve(root);
      if ((stat.children ?? []).length > 0) target = root.resolve(name);
    } catch {
      target = root.resolve(name);
    }
    const files = scaffoldFiles(name, template.value);
    try {
      await this.files.createFolder(target);
      for (const f of files) {
        const uri = target.resolve(f.path);
        const slash = f.path.lastIndexOf('/');
        if (slash > 0) await this.files.createFolder(uri.parent);
        if (await this.files.exists(uri)) {
          this.messages.warn(`Modula-2: ${f.path} already exists, skipped.`);
          continue;
        }
        await this.files.writeFile(uri, BinaryBuffer.fromString(f.content));
      }
    } catch (error) {
      this.messages.error(`Modula-2: cannot scaffold project: ${error instanceof Error ? error.message : String(error)}`);
      return;
    }
    const where = target.toString() === root.toString() ? 'the open folder' : `the "${name}" folder`;
    this.messages.info(`Modula-2: created ${template.label} "${name}" in ${where}. Open modula2.json to review, then Modula-2: Build.`);
  }

  /** Open a project folder (delegates to the workspace folder dialog). */
  protected async openProject(): Promise<void> {
    await this.commands.executeCommand(WorkspaceCommands.OPEN_FOLDER.id);
  }

  /** Switch to a recently opened project (delegates to the recent picker). */
  protected async switchProject(): Promise<void> {
    await this.recordCurrentProject();
    const recent = await this.recentProjects();
    const picks = recent.map(r => ({
      label: r.name, description: r.path, value: r.path,
    }));
    picks.push({ label: 'Browse for folder...', description: 'Open any folder as a project', value: '' });
    const choice = await this.quickInput.showQuickPick(picks, { placeholder: 'Switch to project' });
    if (!choice) return;
    if (!choice.value) {
      await this.commands.executeCommand(WorkspaceCommands.OPEN_FOLDER.id);
      return;
    }
    this.workspace.open(new URI(choice.value));
  }

  /** Remembered Modula-2 projects (most recent first, max 12). */
  protected async recentProjects(): Promise<{ name: string; path: string }[]> {
    try {
      const raw = await this.storage.getData<{ name: string; path: string }[]>('modula2.recentProjects', []);
      if (!Array.isArray(raw)) return [];
      const live: { name: string; path: string }[] = [];
      for (const r of raw) {
        if (!r || typeof r.name !== 'string' || typeof r.path !== 'string') continue;
        try {
          if (await this.files.exists(new URI(r.path))) live.push({ name: r.name, path: r.path });
        } catch { /* drop dead entries */ }
      }
      return live.slice(0, 12);
    } catch {
      return [];
    }
  }

  /** Record the current workspace when it holds a Modula-2 project. */
  protected async recordCurrentProject(): Promise<void> {
    try {
      const roots = await this.workspace.roots;
      if (roots.length === 0) return;
      const root = roots[0].resource;
      const raw = await this.files.read(root.resolve('modula2.json')).catch(() => undefined);
      if (!raw) return;
      const json = JSON.parse(raw.value) as { name?: unknown };
      if (typeof json.name !== 'string' || json.name.length === 0) return;
      const entry = { name: json.name, path: root.toString() };
      const prev = await this.recentProjects();
      const next = [entry, ...prev.filter(r => r.path !== entry.path)].slice(0, 12);
      await this.storage.setData('modula2.recentProjects', next);
    } catch { /* best-effort history */ }
  }

  /** Close the current project (delegates to workspace close). */
  protected async closeProject(): Promise<void> {
    await this.commands.executeCommand(WorkspaceCommands.CLOSE.id);
  }

  protected async validateProject(): Promise<void> {
    const root = await this.root();
    if (!root) return;
    const uri = root.resolve('modula2.json');
    let text: string;
    try {
      text = (await this.files.read(uri)).value;
    } catch {
      this.messages.warn('Modula-2: no modula2.json in the open folder. Create one with Modula-2: New Modula-2 Project.');
      return;
    }
    const problems = validateProjectFile(text);
    if (problems.length > 0) {
      this.messages.error(`Modula-2: invalid project.\n${problems.join('\n')}`);
      return;
    }
    // Existence checks against the workspace.
    let raw: { name: string; main: string; sourceDirectories?: string[]; definitionDirectories?: string[] };
    try {
      raw = JSON.parse(text);
    } catch {
      this.messages.error('Modula-2: invalid project.\nmodula2.json: invalid JSON.');
      return;
    }
    const missing: string[] = [];
    try {
      if (!await this.files.exists(root.resolve(raw.main))) missing.push(`main file "${raw.main}" does not exist`);
    } catch { /* ignore */ }
    for (const key of ['sourceDirectories', 'definitionDirectories'] as const) {
      for (const d of raw[key] ?? []) {
        try {
          if (!await this.files.exists(root.resolve(d))) missing.push(`"${key}" entry "${d}" does not exist`);
        } catch { /* ignore */ }
      }
    }
    if (missing.length > 0) {
      this.messages.error(`Modula-2: project "${raw.name}" has problems.\n${missing.join('\n')}`);
      return;
    }
    this.messages.info(`Modula-2: project "${raw.name}" is valid (main: ${raw.main}).`);
  }
}

class ProjectMenus implements MenuContribution {
  registerMenus(menus: MenuModelRegistry): void {
    const submenu = ['menubar', 'modula2'];
    menus.registerMenuAction(submenu, { commandId: Commands.newModule.id, order: '20' });
    menus.registerMenuAction(submenu, { commandId: Commands.newDefModule.id, order: '21' });
    menus.registerMenuAction(submenu, { commandId: Commands.newProject.id, order: '22' });
    menus.registerMenuAction(submenu, { commandId: Commands.validate.id, order: '23' });
    const project = ['menubar', 'project'];
    menus.registerSubmenu(project, 'Project');
    menus.registerMenuAction(project, { commandId: Commands.newProject.id, order: '10' });
    menus.registerMenuAction(project, { commandId: Commands.newModule.id, order: '11' });
    menus.registerMenuAction(project, { commandId: Commands.newDefModule.id, order: '12' });
    menus.registerMenuAction(project, { commandId: Commands.openProject.id, order: '13' });
    menus.registerMenuAction(project, { commandId: Commands.switchProject.id, order: '14' });
    menus.registerMenuAction(project, { commandId: Commands.closeProject.id, order: '15' });
  }
}

export default new ContainerModule(bind => {
  bind(CommandContribution).to(ProjectCommands).inSingletonScope();
  bind(MenuContribution).to(ProjectMenus).inSingletonScope();
  bindViewContribution(bind, Modula2ExplorerContribution);
  bind(FrontendApplicationContribution).toService(Modula2ExplorerContribution);
  bind(WidgetFactory).toDynamicValue(context => ({
    id: MODULA2_EXPLORER_ID,
    createWidget: () => createModula2ExplorerWidget(context.container),
  }));
  bind(Modula2ExplorerContainerFactory).toSelf().inSingletonScope();
  bind(WidgetFactory).toService(Modula2ExplorerContainerFactory);
  bind(CommandContribution).to(Modula2ExplorerCommands).inSingletonScope();
  bind(MenuContribution).to(Modula2ExplorerMenus).inSingletonScope();
});