import * as Koka from 'koka'
import * as Err from 'koka/err'
import * as Ctx from 'koka/ctx'

// Define your effects
class UserNotFound extends Err.Err('UserNotFound')<string> {}
class AuthToken extends Ctx.Ctx('AuthToken')<string> {}

// Write effectful code
function* getUser(id: string) {
    const token = yield* Ctx.get(AuthToken)

    if (!token) {
        yield* Err.throw(new UserNotFound('No auth token'))
    }

    return { id, name: 'John Doe' }
}

// Handle effects
const program = Koka.try(getUser('123')).handle({
    UserNotFound: (error) => ({ error }),
    AuthToken: 'secret-token',
})

const result = Koka.run(program)

// ✅ Correct import style (as used in tests)
import * as Koka from 'koka'
import * as Err from 'koka/err'
import * as Ctx from 'koka/ctx'
import * as Async from 'koka/async'
import * as Task from 'koka/task'
import * as Result from 'koka/result'
import * as Opt from 'koka/opt'
import * as Gen from 'koka/gen'

// ❌ Not used in this documentation
import { try, run } from 'koka'
import { Err, Ctx } from 'koka'

import * as Koka from 'koka'
import * as Err from 'koka/err'

class ValidationError extends Err.Err('ValidationError')<{ field: string; message: string }> {}

function* validateUser(user: any) {
    if (!user.name) {
        yield* Err.throw(
            new ValidationError({
                field: 'name',
                message: 'Name is required',
            }),
        )
    }
    return user
}

const program = Koka.try(validateUser({})).handle({
    ValidationError: (error) => ({ error, status: 'error' }),
})

const result = Koka.run(program)

import * as Koka from 'koka'
import * as Ctx from 'koka/ctx'
import * as Async from 'koka/async'

class Database extends Ctx.Ctx('Database')<{
    query: (sql: string) => Promise<any>
}> {}

function* getUser(id: string) {
    const db = yield* Ctx.get(Database)
    const user = yield* Async.await(db.query(`SELECT * FROM users WHERE id = '${id}'`))
    return user
}

const program = Koka.try(getUser('123')).handle({
    Database: {
        query: async (sql) => ({ id: '123', name: 'John Doe' }),
    },
})

const result = await Koka.run(program)

import * as Koka from 'koka'
import * as Task from 'koka/task'

function* getUserProfile(userId: string) {
    const result = yield* Task.object({
        user: () => fetchUser(userId),
        posts: () => fetchPosts(userId),
        comments: () => fetchComments(userId),
    })

    return result
}

const profile = await Koka.run(getUserProfile('123'))