package mpvipc

import (
	"context"
	"encoding/json"
	"errors"
	"net"

	"git.milar.in/milarin/channel"
)

type Command struct {
	Command []interface{} `json:"command"`
}

type Response[T any] struct {
	Data      T      `json:"data"`
	RequestID int    `json:"request_id"`
	Error     string `json:"error"`
}

type Event[T any] struct {
	Data   T      `json:"data"`
	ID     int    `json:"id"`
	Name   string `json:"name"`
	Error  string `json:"error"`
	Reason string `json:"reason"`
}

func SendCommand[T any](socket string, cmd *Command) (*Response[T], error) {
	conn, err := net.Dial("unix", socket)
	if err != nil {
		return nil, err
	}
	defer conn.Close()

	if err := json.NewEncoder(conn).Encode(cmd); err != nil {
		return nil, err
	}

	resp := &Response[T]{}
	if err := json.NewDecoder(conn).Decode(resp); err != nil {
		return nil, err
	}

	return resp, nil
}

func GetProperty[T any](socket string, propertyName string) (T, error) {
	cmd := &Command{[]interface{}{"get_property", propertyName}}
	resp, err := SendCommand[T](socket, cmd)
	if err != nil {
		return *new(T), err
	}

	if resp.Error != "success" {
		return *new(T), errors.New(resp.Error)
	}

	return resp.Data, nil
}

func SetProperty[T any](socket string, propertyName string, propertyValue T) error {
	cmd := &Command{[]interface{}{"set_property", propertyName, propertyValue}}
	resp, err := SendCommand[T](socket, cmd)
	if err != nil {
		return err
	}

	if resp.Error != "success" {
		return errors.New(resp.Error)
	}

	return nil
}

func ObserveProperty[T any](ctx context.Context, socket string, propertyName string) (<-chan T, error) {
	ch, err := ObserveEvent[T](ctx, socket, propertyName)
	if err != nil {
		return nil, err
	}

	return channel.MapSuccessive(ch, func(e Event[T]) T { return e.Data }), nil
}

func ObserveEvent[T any](ctx context.Context, socket string, propertyName string) (<-chan Event[T], error) {
	out := make(chan Event[T], 10)

	conn, err := net.Dial("unix", socket)
	if err != nil {
		return nil, err
	}

	enc := json.NewEncoder(conn)
	dec := json.NewDecoder(conn)

	cmd := &Command{[]interface{}{"observe_property", 1, propertyName}}
	if err := enc.Encode(cmd); err != nil {
		conn.Close()
		return nil, err
	}

	resp := &Response[T]{}
	if err := json.NewDecoder(conn).Decode(resp); err != nil {
		conn.Close()
		return nil, err
	}

	if resp.Error != "success" {
		conn.Close()
		return nil, errors.New(resp.Error)
	}

	go func() {
		defer conn.Close()
		defer enc.Encode(&Command{[]interface{}{"unobserve_property", 0}})
		<-ctx.Done()
	}()

	go func() {
		defer close(out)

		for ctx.Err() == nil {
			event := Event[T]{}
			if err := dec.Decode(&event); err != nil {
				break
			}
			out <- event
		}
	}()

	return out, nil
}