import { CommandGroup } from './CommandGroup';
import type { CommandContext, CommandEntry, CommandSpec } from './CommandGroup';
import { NavigationCommands } from '../commands/navigation';
import { TabsMutationCommands } from '../commands/tabs';
import { TabsQueryCommands } from '../commands/tabs-query';
import { GroupsCommands } from '../commands/groups';
import { WindowsCommands } from '../commands/windows';
import { DomCommands } from '../commands/dom';
import { BrowserDataCommands } from '../commands/browser-data';
import { SessionCommands } from '../commands/session';
import { PerfCommands } from '../commands/perf';
import { ExtensionCommands } from '../commands/extension';
import type { CommandArgs, Serializable, DispatchArgs, PageRequest } from '../types';

function isCommandSpec(entry: CommandEntry): entry is CommandSpec {
  return typeof entry !== "function";
}

export function makePagedData(items: Serializable[], page: PageRequest) {
  const total = items.length;
  const offset = Math.max(0, Number(page.offset) || 0);
  const requestedLimit = Math.max(1, Number(page.limit) || 100);
  const limit = Math.min(requestedLimit, 1000);
  const end = Math.min(offset + limit, total);
  return {
    __browserCliPage: true,
    items: items.slice(offset, end),
    offset,
    limit,
    total,
    nextOffset: end < total ? end : null,
  };
}

export class CommandRegistry {
  private readonly entries = new Map<string, CommandEntry>();

  constructor(private readonly ctx: CommandContext) {}

  /** Flattens a group's full-id-keyed commands into the registry map. */
  register(group: CommandGroup): void {
    for (const [command, entry] of Object.entries(group.commands)) {
      if (this.entries.has(command)) {
        throw new Error(`Duplicate command registration: ${command}`);
      }
      this.entries.set(command, entry);
    }
  }

  private resolve(command: string): CommandEntry {
    const entry = this.entries.get(command);
    if (!entry) throw new Error(`Unknown command: ${command}`);
    return entry;
  }

  async dispatch(command: string, args: DispatchArgs, opts: { background?: boolean; page?: PageRequest }): Promise<Serializable> {
    const entry = this.resolve(command);

    if (isCommandSpec(entry) && entry.background && opts.background) {
      // Narrow the dynamic IPC dict to the handler's declared arg type at the
      // call boundary.
      return this.ctx.jobs.start(command, args, jobArgs => Promise.resolve(entry.run(jobArgs as CommandArgs)));
    }

    const run = isCommandSpec(entry) ? entry.run : entry;
    let result = await run(args as CommandArgs);
    if (opts.page && Array.isArray(result)) {
      result = makePagedData(result, opts.page);
    }
    return result;
  }
}

/**
 * Builds the registry and registers every command group. The SessionCommands
 * instance is returned alongside because index.ts wires its lifecycle methods
 * (chrome.tabs.onActivated → activateLazyTab) and NativeConnection references it
 * for the clients.rename_profile reconnect side-effect.
 */
export function assembleRegistry(ctx: CommandContext): { registry: CommandRegistry; session: SessionCommands } {
  const registry = new CommandRegistry(ctx);
  const session = new SessionCommands(ctx);
  registry.register(new NavigationCommands(ctx));
  registry.register(new TabsMutationCommands(ctx));
  registry.register(new TabsQueryCommands(ctx));
  registry.register(new GroupsCommands(ctx));
  registry.register(new WindowsCommands(ctx));
  registry.register(new DomCommands(ctx));
  registry.register(new BrowserDataCommands(ctx));
  registry.register(session);
  registry.register(new PerfCommands(ctx));
  registry.register(new ExtensionCommands(ctx));
  return { registry, session };
}