// Copyright 2022 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package gamepad

import (
	"sync"
	"time"

	"github.com/hajimehoshi/ebiten/v2/internal/gamepaddb"
)

type ID int

const (
	hatCentered  = 0
	hatUp        = 1
	hatRight     = 2
	hatDown      = 4
	hatLeft      = 8
	hatRightUp   = hatRight | hatUp
	hatRightDown = hatRight | hatDown
	hatLeftUp    = hatLeft | hatUp
	hatLeftDown  = hatLeft | hatDown
)

type gamepads struct {
	inited   bool
	gamepads []*Gamepad
	m        sync.Mutex

	native nativeGamepads
}

var theGamepads gamepads

// AppendGamepadIDs is concurrent-safe.
func AppendGamepadIDs(ids []ID) []ID {
	return theGamepads.appendGamepadIDs(ids)
}

// Update is concurrent-safe.
func Update() error {
	return theGamepads.update()
}

// Get is concurrent-safe.
func Get(id ID) *Gamepad {
	return theGamepads.get(id)
}

func SetNativeWindow(nativeWindow uintptr) {
	theGamepads.setNativeWindow(nativeWindow)
}

func (g *gamepads) appendGamepadIDs(ids []ID) []ID {
	g.m.Lock()
	defer g.m.Unlock()

	for i, gp := range g.gamepads {
		if gp != nil {
			ids = append(ids, ID(i))
		}
	}
	return ids
}

func (g *gamepads) update() error {
	g.m.Lock()
	defer g.m.Unlock()

	if !g.inited {
		if err := g.native.init(g); err != nil {
			return err
		}
		g.inited = true
	}

	if err := g.native.update(g); err != nil {
		return err
	}

	// A gamepad can be detected even though there are not. Apparently, some special devices are
	// recognized as gamepads by OSes. In this case, the number of the 'buttons' can exceeds the
	// maximum. Skip such devices as a tentative solution (#1173, #2039).
	g.remove(func(gamepad *Gamepad) bool {
		return gamepad.ButtonCount() > ButtonNum
	})

	for _, gp := range g.gamepads {
		if gp == nil {
			continue
		}
		if err := gp.update(g); err != nil {
			return err
		}
	}
	return nil
}

func (g *gamepads) get(id ID) *Gamepad {
	g.m.Lock()
	defer g.m.Unlock()

	if id < 0 || int(id) >= len(g.gamepads) {
		return nil
	}
	return g.gamepads[id]
}

func (g *gamepads) find(cond func(*Gamepad) bool) *Gamepad {
	for _, gp := range g.gamepads {
		if gp == nil {
			continue
		}
		if cond(gp) {
			return gp
		}
	}
	return nil
}

func (g *gamepads) add(name, sdlID string) *Gamepad {
	for i, gp := range g.gamepads {
		if gp == nil {
			gp := &Gamepad{
				name:  name,
				sdlID: sdlID,
			}
			g.gamepads[i] = gp
			return gp
		}
	}

	gp := &Gamepad{
		name:  name,
		sdlID: sdlID,
	}
	g.gamepads = append(g.gamepads, gp)
	return gp
}

func (g *gamepads) remove(cond func(*Gamepad) bool) {
	for i, gp := range g.gamepads {
		if gp == nil {
			continue
		}
		if cond(gp) {
			g.gamepads[i] = nil
		}
	}
}

func (g *gamepads) setNativeWindow(nativeWindow uintptr) {
	g.m.Lock()
	defer g.m.Unlock()

	var n interface{} = &g.native
	if n, ok := n.(interface{ setNativeWindow(uintptr) }); ok {
		n.setNativeWindow(nativeWindow)
	}
}

type Gamepad struct {
	name  string
	sdlID string
	m     sync.Mutex

	native nativeGamepad
}

func (g *Gamepad) update(gamepads *gamepads) error {
	g.m.Lock()
	defer g.m.Unlock()

	return g.native.update(gamepads)
}

// Name is concurrent-safe.
func (g *Gamepad) Name() string {
	// This is immutable and doesn't have to be protected by a mutex.
	if name := gamepaddb.Name(g.sdlID); name != "" {
		return name
	}
	return g.name
}

// SDLID is concurrent-safe.
func (g *Gamepad) SDLID() string {
	// This is immutable and doesn't have to be protected by a mutex.
	return g.sdlID
}

// AxisCount is concurrent-safe.
func (g *Gamepad) AxisCount() int {
	g.m.Lock()
	defer g.m.Unlock()

	return g.native.axisCount()
}

// ButtonCount is concurrent-safe.
func (g *Gamepad) ButtonCount() int {
	g.m.Lock()
	defer g.m.Unlock()

	return g.native.buttonCount()
}

// HatCount is concurrent-safe.
func (g *Gamepad) HatCount() int {
	g.m.Lock()
	defer g.m.Unlock()

	return g.native.hatCount()
}

// Axis is concurrent-safe.
func (g *Gamepad) Axis(axis int) float64 {
	g.m.Lock()
	defer g.m.Unlock()

	return g.native.axisValue(axis)
}

// Button is concurrent-safe.
func (g *Gamepad) Button(button int) bool {
	g.m.Lock()
	defer g.m.Unlock()

	return g.native.isButtonPressed(button)
}

// Hat is concurrent-safe.
func (g *Gamepad) Hat(hat int) int {
	g.m.Lock()
	defer g.m.Unlock()

	return g.native.hatState(hat)
}

// IsStandardLayoutAvailable is concurrent-safe.
func (g *Gamepad) IsStandardLayoutAvailable() bool {
	g.m.Lock()
	defer g.m.Unlock()

	if gamepaddb.HasStandardLayoutMapping(g.sdlID) {
		return true
	}
	return g.native.hasOwnStandardLayoutMapping()
}

// StandardAxisValue is concurrent-safe.
func (g *Gamepad) StandardAxisValue(axis gamepaddb.StandardAxis) float64 {
	if gamepaddb.HasStandardLayoutMapping(g.sdlID) {
		return gamepaddb.AxisValue(g.sdlID, axis, g)
	}
	if g.native.hasOwnStandardLayoutMapping() {
		return g.native.axisValue(int(axis))
	}
	return 0
}

// StandardButtonValue is concurrent-safe.
func (g *Gamepad) StandardButtonValue(button gamepaddb.StandardButton) float64 {
	if gamepaddb.HasStandardLayoutMapping(g.sdlID) {
		return gamepaddb.ButtonValue(g.sdlID, button, g)
	}
	if g.native.hasOwnStandardLayoutMapping() {
		return g.native.buttonValue(int(button))
	}
	return 0
}

// IsStandardButtonPressed is concurrent-safe.
func (g *Gamepad) IsStandardButtonPressed(button gamepaddb.StandardButton) bool {
	if gamepaddb.HasStandardLayoutMapping(g.sdlID) {
		return gamepaddb.IsButtonPressed(g.sdlID, button, g)
	}
	if g.native.hasOwnStandardLayoutMapping() {
		return g.native.isButtonPressed(int(button))
	}
	return false
}

// Vibrate is concurrent-safe.
func (g *Gamepad) Vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
	g.m.Lock()
	defer g.m.Unlock()

	g.native.vibrate(duration, strongMagnitude, weakMagnitude)
}