package org.openrndr.extras.camera

import org.openrndr.*
import org.openrndr.math.Vector2
import org.openrndr.math.Vector3
import org.openrndr.math.asRadians
import kotlin.math.PI
import kotlin.math.abs
import kotlin.math.tan

class OrbitalControls(val orbitalCamera: OrbitalCamera, val userInteraction: Boolean = true, val keySpeed: Double = 1.0) : Extension {
    enum class STATE {
        NONE,
        ROTATE,
        PAN,
    }

    private var state = STATE.NONE
    var fov = orbitalCamera.fov

    private lateinit var program: Program
    private lateinit var lastMousePosition: Vector2

    private fun mouseScrolled(event: MouseEvent) {
        if (!event.propagationCancelled) {

            if (orbitalCamera.projectionType == ProjectionType.PERSPECTIVE) {
                if (abs(event.rotation.x) > 0.1) return
                when {
                    event.rotation.y > 0 -> orbitalCamera.dollyIn()
                    event.rotation.y < 0 -> orbitalCamera.dollyOut()
                }
            } else {
                if (abs(event.rotation.x) > 0.1) return
                when {
                    event.rotation.y > 0 -> orbitalCamera.scale(1.0)
                    event.rotation.y < 0 -> orbitalCamera.scale(-1.0)
                }
            }
        }
    }

    private fun mouseMoved(event: MouseEvent) {

        if (!event.propagationCancelled) {
            if (state == STATE.NONE) return
            val delta = lastMousePosition - event.position
            lastMousePosition = event.position

            if (state == STATE.PAN) {

                val offset = Vector3.fromSpherical(orbitalCamera.spherical) - orbitalCamera.lookAt

                // half of the fov is center to top of screen
                val targetDistance = offset.length * tan(fov / 2).asRadians
                val panX = (2 * delta.x * targetDistance / program.window.size.x)
                val panY = (2 * delta.y * targetDistance / program.window.size.y)

                orbitalCamera.pan(panX, -panY, 0.0)

            } else {
                val rotX = 360.0 * delta.x / program.window.size.x
                val rotY = 360.0 * delta.y / program.window.size.y
                orbitalCamera.rotate(rotX, rotY)
            }
        }
    }

    private fun mouseButtonDown(event: MouseEvent) {
        if (!event.propagationCancelled) {
            val previousState = state

            when (event.button) {
                MouseButton.LEFT -> {
                    state = STATE.ROTATE
                }
                MouseButton.RIGHT -> {
                    state = STATE.PAN
                }
                MouseButton.CENTER -> {
                }
                MouseButton.NONE -> {
                }
            }

            if (previousState == STATE.NONE) {
                lastMousePosition = event.position
            }
        }
    }

    fun keyPressed(keyEvent: KeyEvent) {
        if (!keyEvent.propagationCancelled) {
            if (keyEvent.key == KEY_ARROW_RIGHT) {
                orbitalCamera.pan(keySpeed, 0.0, 0.0)
            }
            if (keyEvent.key == KEY_ARROW_LEFT) {
                orbitalCamera.pan(-keySpeed, 0.0, 0.0)
            }
            if (keyEvent.key == KEY_ARROW_UP) {
                orbitalCamera.pan(0.0, keySpeed, 0.0)
            }
            if (keyEvent.key == KEY_ARROW_DOWN) {
                orbitalCamera.pan(0.0, -keySpeed, 0.0)
            }

            if (keyEvent.name == "q") {
                orbitalCamera.pan(0.0, -keySpeed, 0.0)
            }
            if (keyEvent.name == "e") {
                orbitalCamera.pan(0.0, keySpeed, 0.0)
            }
            if (keyEvent.name == "w") {
                orbitalCamera.pan(0.0, 0.0, -keySpeed)
            }
            if (keyEvent.name == "s") {
                orbitalCamera.pan(0.0, 0.0, keySpeed)
            }
            if (keyEvent.name == "a") {
                orbitalCamera.pan(-keySpeed, 0.0, 0.0)
            }
            if (keyEvent.name == "d") {
                orbitalCamera.pan(keySpeed, 0.0, 0.0)
            }

            if (keyEvent.key == KEY_PAGE_UP) {
                orbitalCamera.zoom(keySpeed)
            }
            if (keyEvent.key == KEY_PAGE_DOWN) {
                orbitalCamera.zoom(-keySpeed)
            }
        }
    }

    // EXTENSION
    override var enabled: Boolean = true

    override fun setup(program: Program) {
        this.program = program

        if (userInteraction) {
            program.mouse.moved.listen { mouseMoved(it) }
            program.mouse.buttonDown.listen { mouseButtonDown(it) }
            program.mouse.buttonUp.listen { state = STATE.NONE }
            program.mouse.scrolled.listen { mouseScrolled(it) }
            program.keyboard.keyDown.listen { keyPressed(it) }
            program.keyboard.keyRepeat.listen { keyPressed(it) }
        }
    }
}