package main

import (
	"encoding/json"
	"fmt"
	"log"
	"strings"
	"time"

	"github.com/goplus/llgo/x/io"
)

// -----------------------------------------------------------------------------

type Response struct {
	StatusCode int

	mockBody string
}

func (r *Response) mock(body string) {
	r.mockBody = body
}

func (r *Response) Text() (resolve io.Promise[string]) {
	resolve(r.mockBody, nil)
	return
}

func (r *Response) TextCompiled() *io.PromiseImpl[string] {
	P := &io.PromiseImpl[string]{}
	P.Debug = "Text"
	P.Func = func(resolve func(string, error)) {
		for {
			switch P.Prev = P.Next; P.Prev {
			case 0:
				P.Next = -1
				resolve(r.mockBody, nil)
				return
			default:
				panic("Promise already done")
			}
		}
	}
	return P
}

func Http(method string, url string, callback func(resp *Response, err error)) {
	go func() {
		body := ""
		if strings.HasPrefix(url, "http://example.com/user/") {
			name := url[len("http://example.com/user/"):]
			body = `{"name":"` + name + `"}`
		} else if strings.HasPrefix(url, "http://example.com/score/") {
			body = "99.5"
		}
		time.Sleep(200 * time.Millisecond)
		resp := &Response{StatusCode: 200, mockBody: body}
		callback(resp, nil)
	}()
}

func AsyncHttpGet(url string) (resolve io.Promise[*Response]) {
	Http("GET", url, resolve)
	return
}

func AsyncHttpGetCompiled(url string) *io.PromiseImpl[*Response] {
	P := &io.PromiseImpl[*Response]{}
	P.Debug = "HttpGet"
	P.Func = func(resolve func(*Response, error)) {
		for {
			switch P.Prev = P.Next; P.Prev {
			case 0:
				P.Next = -1
				Http("GET", url, resolve)
				return
			default:
				panic("Promise already done")
			}
		}
	}
	return P
}

func AsyncHttpPost(url string) (resolve io.Promise[*Response]) {
	Http("POST", url, resolve)
	return
}

func AsyncHttpPostCompiled(url string) *io.PromiseImpl[*Response] {
	P := &io.PromiseImpl[*Response]{}
	P.Debug = "HttpPost"
	P.Func = func(resolve func(*Response, error)) {
		for {
			switch P.Prev = P.Next; P.Prev {
			case 0:
				P.Next = -1
				Http("POST", url, resolve)
				return
			default:
				panic("Promise already done")
			}
		}
	}
	return P
}

// -----------------------------------------------------------------------------

type User struct {
	Name string
}

func GetUser(name string) (resolve io.Promise[User]) {
	resp, err := AsyncHttpGet("http://example.com/user/" + name).Await()
	if err != nil {
		resolve(User{}, err)
		return
	}

	if resp.StatusCode != 200 {
		resolve(User{}, fmt.Errorf("http status code: %d", resp.StatusCode))
		return
	}

	body, err := resp.Text().Await()
	if err != nil {
		resolve(User{}, err)
		return
	}
	user := User{}
	if err := json.Unmarshal([]byte(body), &user); err != nil {
		resolve(User{}, err)
		return
	}

	resolve(user, nil)
	return
}

func GetUserCompiled(name string) *io.PromiseImpl[User] {
	var state1 *io.PromiseImpl[*Response]
	var state2 *io.PromiseImpl[string]

	P := &io.PromiseImpl[User]{}
	P.Debug = "GetUser"
	P.Func = func(resolve func(User, error)) {
		for {
			switch P.Prev = P.Next; P.Prev {
			case 0:
				P.Next = 1
				state1 = AsyncHttpGetCompiled("http://example.com/user/" + name)
				state1.Exec = P.Exec
				state1.Call()
				return
			case 1:
				if !state1.Done() {
					state1.Call()
					return
				}
				P.Next = 2
				resp, err := state1.Value, state1.Err
				log.Printf("resp: %v, err: %v\n", resp, err)
				if err != nil {
					resolve(User{}, err)
					return
				}

				if resp.StatusCode != 200 {
					resolve(User{}, fmt.Errorf("http status code: %d", resp.StatusCode))
					return
				}

				state2 = resp.TextCompiled()
				state2.Exec = P.Exec
				state2.Call()
				log.Printf("TextCompiled state2: %v\n", state2)
				return
			case 2:
				if !state2.Done() {
					state2.Call()
					return
				}
				P.Next = -1
				body, err := state2.Value, state2.Err
				if err != nil {
					resolve(User{}, err)
					return
				}
				user := User{}
				log.Printf("body: %v\n", body)
				if err := json.Unmarshal([]byte(body), &user); err != nil {
					resolve(User{}, err)
					return
				}

				resolve(user, nil)
				return
			default:
				panic(fmt.Sprintf("Promise already done, %+v", P))
			}
		}
	}
	return P
}

func GetScore() (resolve io.Promise[float64]) {
	resp, err := AsyncHttpGet("http://example.com/score/").Await()
	if err != nil {
		resolve(0, err)
		return
	}

	if resp.StatusCode != 200 {
		resolve(0, fmt.Errorf("http status code: %d", resp.StatusCode))
		return
	}

	body, err := resp.Text().Await()
	if err != nil {
		resolve(0, err)
		return
	}

	score := 0.0
	if _, err := fmt.Sscanf(body, "%f", &score); err != nil {
		resolve(0, err)
		return
	}
	resolve(score, nil)
	return
}

func GetScoreCompiled() *io.PromiseImpl[float64] {
	var state1 *io.PromiseImpl[*Response]
	var state2 *io.PromiseImpl[string]

	P := &io.PromiseImpl[float64]{}
	P.Debug = "GetScore"
	P.Func = func(resolve func(float64, error)) {
		for {
			switch P.Prev = P.Next; P.Prev {
			case 0:
				P.Next = 1
				state1 = AsyncHttpGetCompiled("http://example.com/score/")
				state1.Exec = P.Exec
				state1.Call()
				return
			case 1:
				if !state1.Done() {
					state1.Call()
					return
				}
				P.Next = 2
				resp, err := state1.Value, state1.Err
				if err != nil {
					resolve(0, err)
					return
				}

				if resp.StatusCode != 200 {
					resolve(0, fmt.Errorf("http status code: %d", resp.StatusCode))
					return
				}

				state2 = resp.TextCompiled()
				state2.Exec = P.Exec
				state2.Call()

				return
			case 2:
				if !state2.Done() {
					state2.Call()
					return
				}
				P.Next = -1
				body, err := state2.Value, state2.Err
				if err != nil {
					resolve(0, err)
					return
				}

				score := 0.0
				if _, err := fmt.Sscanf(body, "%f", &score); err != nil {
					resolve(0, err)
					return
				}
				resolve(score, nil)
				return
			default:
				panic("Promise already done")
			}
		}
	}
	return P
}

func DoUpdate(op string) (resolve io.Promise[io.Void]) {
	resp, err := AsyncHttpPost("http://example.com/update/" + op).Await()
	if err != nil {
		resolve(io.Void{}, err)
		return
	}

	if resp.StatusCode != 200 {
		resolve(io.Void{}, fmt.Errorf("http status code: %d", resp.StatusCode))
		return
	}

	resolve(io.Void{}, nil)
	return
}

func DoUpdateCompiled(op string) *io.PromiseImpl[io.Void] {
	var state1 *io.PromiseImpl[*Response]

	P := &io.PromiseImpl[io.Void]{}
	P.Debug = "DoUpdate"
	P.Func = func(resolve func(io.Void, error)) {
		for {
			switch P.Prev = P.Next; P.Prev {
			case 0:
				P.Next = 1
				state1 = AsyncHttpPostCompiled("http://example.com/update/" + op)
				state1.Exec = P.Exec
				state1.Call()
				return
			case 1:
				if !state1.Done() {
					state1.Call()
					return
				}
				P.Next = -1
				resp, err := state1.Value, state1.Err
				if err != nil {
					resolve(io.Void{}, err)
					return
				}

				if resp.StatusCode != 200 {
					resolve(io.Void{}, fmt.Errorf("http status code: %d", resp.StatusCode))
					return
				}

				resolve(io.Void{}, nil)
				return
			default:
				panic("Promise already done")
			}
		}
	}
	return P
}

func Demo() (resolve io.Promise[io.Void]) {
	user, err := GetUser("1").Await()
	log.Println(user, err)

	user, err = io.Race[User](GetUser("2"), GetUser("3"), GetUser("4")).Await()
	log.Println(user, err)

	users, err := io.All[User]([]io.AsyncCall[User]{GetUser("5"), GetUser("6"), GetUser("7")}).Await()
	log.Println(users, err)

	user, score, _, err := io.Await3[User, float64, io.Void](GetUser("8"), GetScore(), DoUpdate("update sth."))
	log.Println(user, score, err)

	// TODO(lijie): select from multiple promises without channel
	// select {
	// case user := <-GetUser("123").Chan():
	// 	log.Println("user:", user)
	// case score := <-GetScore().Chan():
	// 	log.Println("score:", score)
	// case <-io.Timeout(5 * time.Second).Chan():
	// 	log.Println("timeout")
	// }
	return
}

func DemoCompiled() *io.PromiseImpl[io.Void] {
	var state1 *io.PromiseImpl[User]
	var state2 *io.PromiseImpl[User]
	var state3 *io.PromiseImpl[[]io.Result[User]]
	var state4 *io.PromiseImpl[io.Await3Result[User, float64, io.Void]]

	P := &io.PromiseImpl[io.Void]{}
	P.Debug = "Demo"
	P.Func = func(resolve func(io.Void, error)) {
		for {
			switch P.Prev = P.Next; P.Prev {
			case 0:
				P.Next = 1
				state1 = GetUserCompiled("1")
				state1.Exec = P.Exec
				state1.Call()
				return
			case 1:
				if !state1.Done() {
					state1.Call()
					return
				}
				P.Next = 2
				user, err := state1.Value, state1.Err
				log.Printf("user: %v, err: %v\n", user, err)

				state2 = io.Race[User](GetUserCompiled("2"), GetUserCompiled("3"), GetUserCompiled("4"))
				log.Printf("state2: %v\n", state2)
				state2.Exec = P.Exec
				state2.Call()
				return
			case 2:

				if !state2.Done() {
					state2.Call()
					return
				}
				log.Printf("case 2, state2: %+v\n", state2)

				P.Next = 3
				user, err := state2.Value, state2.Err
				log.Printf("race user: %v, err: %v\n", user, err)

				state3 = io.All[User]([]io.AsyncCall[User]{GetUserCompiled("5"), GetUserCompiled("6"), GetUserCompiled("7")})
				log.Printf("state3: %v\n", state3)
				state3.Exec = P.Exec
				state3.Call()
				return
			case 3:
				if !state3.Done() {
					state3.Call()
					return
				}

				P.Next = 4
				users, err := state3.Value, state3.Err
				log.Println(users, err)

				state4 = io.Await3Compiled[User, float64, io.Void](GetUserCompiled("8"), GetScoreCompiled(), DoUpdateCompiled("update sth."))
				log.Printf("state4: %v\n", state4)
				state4.Exec = P.Exec
				state4.Call()
				return
			case 4:
				if !state4.Done() {
					state4.Call()
					return
				}

				P.Next = -1
				user, score, _, err := state4.Value.V1, state4.Value.V2, state4.Value.V3, state4.Value.Err
				log.Println(user, score, err)
				resolve(io.Void{}, nil)
				return
			default:
				panic("Promise already done")
			}
		}
	}
	return P
}

func main() {
	log.SetFlags(log.Lshortfile | log.LstdFlags)
	// io.Run(Demo())
	v, err := io.Run[io.Void](DemoCompiled())
	log.Println(v, err)
}