// 客户端输入处理：键鼠状态采集（UI与输入.md §6）。
//
// 设计：回调只更新状态，游戏逻辑在 tick 里消费状态（主循环解耦）。
package main

import (
	"math"

	"mc/internal/game"
	"mc/internal/physics"

	"github.com/go-gl/glfw/v3.3/glfw"
)

// inputState 键鼠输入状态。
type inputState struct {
	win *glfw.Window

	// 按键状态
	forward, back, left, right, jump, sneak, sprint bool

	// 鼠标
	lastX, lastY float64
	firstMouse   bool
	dyaw, dpitch float64 // 累计角度增量（弧度，tick 消费）

	// 按键事件（tick 消费）
	breakDown  bool
	breakHeld  bool
	placeDown  bool
	selectSlot int // -1 无
}

// newInputState 创建输入状态并注册回调。
func newInputState(win *glfw.Window) *inputState {
	in := &inputState{win: win, firstMouse: true, selectSlot: -1}
	win.SetKeyCallback(in.keyCallback)
	win.SetMouseButtonCallback(in.mouseButtonCallback)
	win.SetCursorPosCallback(in.cursorCallback)
	win.SetScrollCallback(in.scrollCallback)
	return in
}

// keyCallback 键盘回调（动作映射：WASD/空格/Shift/Ctrl/Esc）。
func (in *inputState) keyCallback(_ *glfw.Window, key glfw.Key, _ int, action glfw.Action, _ glfw.KeyMods) {
	down := action != glfw.Release
	switch key {
	case glfw.KeyW:
		in.forward = down
	case glfw.KeyS:
		in.back = down
	case glfw.KeyA:
		in.left = down
	case glfw.KeyD:
		in.right = down
	case glfw.KeySpace:
		in.jump = down
	case glfw.KeyLeftShift:
		in.sneak = down
	case glfw.KeyLeftControl:
		in.sprint = down
	case glfw.KeyEscape:
		if action == glfw.Press {
			in.win.SetShouldClose(true)
		}
	case glfw.Key1, glfw.Key2, glfw.Key3, glfw.Key4, glfw.Key5, glfw.Key6, glfw.Key7, glfw.Key8, glfw.Key9:
		if action == glfw.Press {
			in.selectSlot = int(key) - int(glfw.Key1)
		}
	}
}

// mouseButtonCallback 鼠标按键：左键破坏（按住累积）、右键放置（UI与输入.md §6 长按）。
func (in *inputState) mouseButtonCallback(_ *glfw.Window, button glfw.MouseButton, action glfw.Action, _ glfw.ModifierKey) {
	switch button {
	case glfw.MouseButtonLeft:
		if action == glfw.Press {
			in.breakDown = true
		}
		in.breakHeld = action != glfw.Release
	case glfw.MouseButtonRight:
		if action == glfw.Press {
			in.placeDown = true
		}
	}
}

// cursorCallback 鼠标移动：yaw/pitch 累积（渲染.md §2 主线程消费）。
func (in *inputState) cursorCallback(_ *glfw.Window, x, y float64) {
	if in.firstMouse {
		in.lastX, in.lastY = x, y
		in.firstMouse = false
		return
	}
	dx, dy := x-in.lastX, y-in.lastY
	in.lastX, in.lastY = x, y
	const sens = 0.0025
	in.dyaw += dx * sens
	in.dpitch -= dy * sens
	if in.dpitch > math.Pi/2-0.01 {
		in.dpitch = math.Pi/2 - 0.01
	}
	if in.dpitch < -math.Pi/2+0.01 {
		in.dpitch = -math.Pi/2 + 0.01
	}
}

// scrollCallback 滚轮切热键栏（UI与输入.md §6）。
func (in *inputState) scrollCallback(_ *glfw.Window, _, yoff float64) {
	if yoff > 0 {
		in.selectSlot = -2 // 上滚
	} else if yoff < 0 {
		in.selectSlot = -3 // 下滚
	}
}

// apply 每 tick 把输入状态转成玩家动作（game.Session 驱动）。
func (in *inputState) apply(s *game.Session) {
	cam := s.Cam
	p := s.Player

	// 视角
	if in.dyaw != 0 || in.dpitch != 0 {
		cam.Yaw += in.dyaw
		cam.Pitch += in.dpitch
		in.dyaw, in.dpitch = 0, 0
	}

	// 水平移动（物理与碰撞.md §3：走/冲刺/潜行）
	f := cam.Forward()
	r := cam.Right()
	wish := [2]float64{}
	if in.forward {
		wish[0] += f[0]
		wish[1] += f[2]
	}
	if in.back {
		wish[0] -= f[0]
		wish[1] -= f[2]
	}
	if in.right {
		wish[0] += r[0]
		wish[1] += r[2]
	}
	if in.left {
		wish[0] -= r[0]
		wish[1] -= r[2]
	}
	speed := 4.3
	if in.sprint {
		speed *= 1.3
	}
	if in.sneak {
		speed *= 0.3
	}
	l := math.Sqrt(wish[0]*wish[0] + wish[1]*wish[1])
	if l > 0 {
		p.Vel[0] = wish[0] / l * speed
		p.Vel[2] = wish[1] / l * speed
	} else {
		p.Vel[0] = 0
		p.Vel[2] = 0
	}

	// 跳跃
	if in.jump && p.OnGround {
		p.Jump()
	}

	// 热键栏切换
	switch in.selectSlot {
	case -2:
		s.Inv.Selected = (s.Inv.Selected + 1) % 9
	case -3:
		s.Inv.Selected = (s.Inv.Selected + 8) % 9
	default:
		if in.selectSlot >= 0 && in.selectSlot < 9 {
			s.Inv.Selected = in.selectSlot
		}
	}
	in.selectSlot = -1

	// 破坏（按住累积，方块交互与动画.md §3）
	if in.breakDown {
		s.BeginBreak()
		in.breakDown = false
	}
	if !in.breakHeld && s.BreakProgress() != 0 {
		s.EndBreak()
	}

	// 放置
	if in.placeDown {
		s.PlaceSelected()
		in.placeDown = false
	}
}

var _ = physics.Player{} // 保持引用（后续输入扩展用）