import type { Command, CommandSchema } from './types';
import type {CommandResult, CommandRunner, CommandRunnerContext, CommandRunnerEvents, PromptEvent} from './command-runner';
import { parseCommand } from './command-parse';
import { applyCommandSchema } from './command-validate';
import { parseCommandSchema } from './schema-parse';
import {AsyncQueue} from "@/utils/async-queue";

type CanRunParsed = {
    runParsed<T=unknown>(command: Command): Promise<CommandResult<T>>,
}

type CmdFunc<TContext> = (ctx: TContext, ...args: any[]) => Promise<unknown>;
export class CommandRegistry<TContext> extends Map<string, CommandRunner<TContext>>{
    register<TFunc extends CmdFunc<TContext> = CmdFunc<TContext>>(schema: CommandSchema | string, run: TFunc) {
        const parsedSchema = typeof schema === 'string' ? parseCommandSchema(schema) : schema;
        registerCommand(this, {
            schema: parsedSchema,
            async run(this: CommandRunnerContext<TContext>, command: Command){
                const params = command.params;
                return await run.call(this.context, this.context, ...params);
            },
        });

        type TParams = TFunc extends (ctx: TContext, ...args: infer X) => Promise<unknown> ? X : null;
        type TResult = TFunc extends (ctx: TContext, ...args: any[]) => Promise<infer X> ? X : null;
        return function(ctx: TContext & CanRunParsed, ...args: TParams){
            return ctx.runParsed({
                options: {},
                params: args,
                flags: {},
                name: parsedSchema.name,
            }) as Promise<CommandResult<TResult>>;
        }
    }
}

export function createCommandRegistry<TContext>(): CommandRegistry<TContext> {
    return new CommandRegistry();
}

export function registerCommand<TContext, TResult>(
    registry: CommandRegistry<TContext>,
    runner: CommandRunner<TContext, TResult>
): void {
    registry.set(runner.schema.name, runner as CommandRunner<TContext, unknown>);
}

export function unregisterCommand<TContext>(
    registry: CommandRegistry<TContext>,
    name: string
): void {
    registry.delete(name);
}

export function hasCommand<TContext>(
    registry: CommandRegistry<TContext>,
    name: string
): boolean {
    return registry.has(name);
}

export function getCommand<TContext>(
    registry: CommandRegistry<TContext>,
    name: string
): CommandRunner<TContext, unknown> | undefined {
    return registry.get(name);
}

type PromptListener = (e: PromptEvent) => void;
type PromptEndListener = () => void;

export type CommandRunnerContextExport<TContext> = CommandRunnerContext<TContext> & {
    registry: CommandRegistry<TContext>;
    promptQueue: AsyncQueue<PromptEvent>;
    _activePrompt: PromptEvent | null;
    _tryCommit: (commandOrInput: Command | string) => string | null;
    _cancel: (reason?: string) => void;
    _pendingInput: string | null;
};

export function createCommandRunnerContext<TContext>(
    registry: CommandRegistry<TContext>,
    context: TContext
): CommandRunnerContextExport<TContext> {
    const promptListeners = new Set<PromptListener>();
    const promptEndListeners = new Set<PromptEndListener>();

    const emitPromptEnd = () => {
        for (const listener of promptEndListeners) {
            listener();
        }
    };

    const on = <T extends keyof CommandRunnerEvents>(_event: T, listener: (e: CommandRunnerEvents[T]) => void) => {
        if (_event === 'prompt') {
            promptListeners.add(listener as PromptListener);
        } else {
            promptEndListeners.add(listener as PromptEndListener);
        }
    };

    const off = <T extends keyof CommandRunnerEvents>(_event: T, listener: (e: CommandRunnerEvents[T]) => void) => {
        if (_event === 'prompt') {
            promptListeners.delete(listener as PromptListener);
        } else {
            promptEndListeners.delete(listener as PromptEndListener);
        }
    };

    let activePrompt: PromptEvent | null = null;

    const tryCommit = (commandOrInput: Command | string) => {
        if (activePrompt) {
            const result = activePrompt.tryCommit(commandOrInput);
            if (result === null) {
                activePrompt = null;
                emitPromptEnd();
            }
            return result;
        }
        return 'No active prompt';
    };

    const cancel = (reason?: string) => {
        if (activePrompt) {
            activePrompt.cancel(reason);
            activePrompt = null;
            emitPromptEnd();
        }
    };

    const prompt = (
        schema: CommandSchema | string,
        validator?: (command: Command) => string | null,
        currentPlayer?: string | null
    ): Promise<Command> => {
        const resolvedSchema = typeof schema === 'string' ? parseCommandSchema(schema) : schema;
        return new Promise((resolve, reject) => {
            const tryCommit = (commandOrInput: Command | string) => {
                const command = typeof commandOrInput === 'string' ? parseCommand(commandOrInput) : commandOrInput;
                const schemaResult = applyCommandSchema(command, resolvedSchema);
                if (!schemaResult.valid) {
                    return schemaResult.errors.join('; ');
                }
                const error = validator?.(schemaResult.command);
                if (error) return error;
                resolve(schemaResult.command);
                return null;
            };
            const cancel = (reason?: string) => {
                activePrompt = null;
                emitPromptEnd();
                reject(new Error(reason ?? 'Cancelled'));
            };
            activePrompt = { schema: resolvedSchema, currentPlayer: currentPlayer ?? null, tryCommit, cancel };
            const event: PromptEvent = { schema: resolvedSchema, currentPlayer: currentPlayer ?? null, tryCommit, cancel };
            for (const listener of promptListeners) {
                listener(event);
            }
        });
    };

    const runnerCtx: CommandRunnerContextExport<TContext> = {
        registry,
        context,
        run: <T=unknown>(input: string) => runCommandWithContext(runnerCtx, input) as Promise<CommandResult<T>>,
        runParsed: <T=unknown>(command: Command) => runCommandParsedWithContext(runnerCtx, command) as Promise<CommandResult<T>>,
        prompt,
        on,
        off,
        _activePrompt: null,
        _tryCommit: tryCommit,
        _cancel: cancel,
        _pendingInput: null,
        promptQueue: null!
    };

    Object.defineProperty(runnerCtx, '_activePrompt', {
        get: () => activePrompt,
    });
    
    let promptQueue: AsyncQueue<PromptEvent>;
    Object.defineProperty(runnerCtx, 'promptQueue', {
        get(){
            if (!promptQueue) {
                promptQueue = new AsyncQueue();
                promptListeners.add(async (event) => {
                    promptQueue.push(event);
                });
            }
            return promptQueue;
        }
    });

    return runnerCtx;
}

async function executeWithRunnerContext<TContext>(
    runnerCtx: CommandRunnerContextExport<TContext>,
    runner: CommandRunner<TContext, unknown>,
    command: Command
): Promise<CommandResult> {
    try {
        const result = await runner.run.call(runnerCtx, command);
        return { success: true, result };
    } catch (e) {
        const error = e as Error;
        return { success: false, error: error.message };
    }
}

export async function runCommand<TContext>(
    registry: CommandRegistry<TContext>,
    context: TContext,
    input: string
): Promise<CommandResult> {
    const runnerCtx = createCommandRunnerContext(registry, context);
    return await runCommandWithContext(runnerCtx, input);
}

async function runCommandWithContext<TContext>(
    runnerCtx: CommandRunnerContextExport<TContext>,
    input: string
): Promise<{ success: true; result: unknown } | { success: false; error: string }> {
    const command = parseCommand(input);
    return await runCommandParsedWithContext(runnerCtx, command);
}

export async function runCommandParsed<TContext>(
    registry: CommandRegistry<TContext>,
    context: TContext,
    command: Command
): Promise<CommandResult> {
    const runnerCtx = createCommandRunnerContext(registry, context);
    return await runCommandParsedWithContext(runnerCtx, command);
}

async function runCommandParsedWithContext<TContext>(
    runnerCtx: CommandRunnerContextExport<TContext>,
    command: Command
): Promise<CommandResult> {
    const runner = runnerCtx.registry.get(command.name);
    if (!runner) {
        return { success: false, error: `Unknown command: ${command.name}` };
    }

    const validationResult = applyCommandSchema(command, runner.schema);
    if (!validationResult.valid) {
        return { success: false, error: validationResult.errors.join('; ') };
    }

    return await executeWithRunnerContext(runnerCtx, runner, validationResult.command);
}