import { createSelectorHook, createState } from "@state-designer/react"
import { clamp, getCommonBounds, screenToWorld } from "utils/utils"
import * as vec from "utils/vec"
import { Bounds, Data, PointerInfo, Shape, ShapeType } from "types"
import { defaultDocument } from "./data"
import Shapes from "lib/shapes"
import history from "state/history"
import * as Sessions from "./sessions"

const initialData: Data = {
  isReadOnly: false,
  camera: {
    point: [0, 0],
    zoom: 1,
  },
  brush: undefined,
  pointedId: null,
  selectedIds: new Set([]),
  currentPageId: "page0",
  document: defaultDocument,
}

const state = createState({
  data: initialData,
  on: {
    ZOOMED_CAMERA: {
      do: "zoomCamera",
    },
    PANNED_CAMERA: {
      do: "panCamera",
    },
  },
  initial: "selecting",
  states: {
    selecting: {
      on: {
        UNDO: { do: "undo" },
        REDO: { do: "redo" },
      },
      initial: "notPointing",
      states: {
        notPointing: {
          on: {
            POINTED_CANVAS: { to: "brushSelecting" },
            POINTED_BOUNDS: { to: "pointingBounds" },
            POINTED_SHAPE: [
              "setPointedId",
              {
                if: "isPressingShiftKey",
                then: {
                  if: "isPointedShapeSelected",
                  do: "pullPointedIdFromSelectedIds",
                  else: {
                    do: "pushPointedIdToSelectedIds",
                    to: "pointingBounds",
                  },
                },
                else: [
                  {
                    unless: "isPointedShapeSelected",
                    do: ["clearSelectedIds", "pushPointedIdToSelectedIds"],
                  },
                  {
                    to: "pointingBounds",
                  },
                ],
              },
            ],
          },
        },
        pointingBounds: {
          on: {
            STOPPED_POINTING: [
              {
                unless: ["isPointingBounds", "isPressingShiftKey"],
                do: ["clearSelectedIds", "pushPointedIdToSelectedIds"],
              },
              { to: "notPointing" },
            ],
            MOVED_POINTER: {
              unless: "isReadOnly",
              if: "distanceImpliesDrag",
              to: "draggingSelection",
            },
          },
        },
        draggingSelection: {
          onEnter: "startTranslateSession",
          on: {
            MOVED_POINTER: "updateTranslateSession",
            PANNED_CAMERA: "updateTranslateSession",
            STOPPED_POINTING: { do: "completeSession", to: "selecting" },
            CANCELLED: { do: "cancelSession", to: "selecting" },
          },
        },
        brushSelecting: {
          onEnter: [
            { unless: "isPressingShiftKey", do: "clearSelectedIds" },
            "startBrushSession",
          ],
          on: {
            MOVED_POINTER: "updateBrushSession",
            PANNED_CAMERA: "updateBrushSession",
            STOPPED_POINTING: { do: "completeSession", to: "selecting" },
            CANCELLED: { do: "cancelSession", to: "selecting" },
          },
        },
      },
    },
  },
  conditions: {
    isPointingBounds(data, payload: PointerInfo) {
      return payload.target === "bounds"
    },
    isReadOnly(data) {
      return data.isReadOnly
    },
    distanceImpliesDrag(data, payload: PointerInfo) {
      return vec.dist2(payload.origin, payload.point) > 16
    },
    isPointedShapeSelected(data) {
      return data.selectedIds.has(data.pointedId)
    },
    isPressingShiftKey(data, payload: { shiftKey: boolean }) {
      return payload.shiftKey
    },
  },
  actions: {
    // History
    enableHistory() {
      history.enable()
    },
    disableHistory() {
      history.disable()
    },
    undo(data) {
      history.undo(data)
    },
    redo(data) {
      history.redo(data)
    },

    // Sessions
    cancelSession(data) {
      session.cancel(data)
      session = undefined
    },
    completeSession(data) {
      session.complete(data)
      session = undefined
    },

    // Brushing
    startBrushSession(data, payload: PointerInfo) {
      session = new Sessions.BrushSession(
        data,
        screenToWorld(payload.point, data)
      )
    },
    updateBrushSession(data, payload: PointerInfo) {
      session.update(data, screenToWorld(payload.point, data))
    },
    // Dragging / Translating
    startTranslateSession(data, payload: PointerInfo) {
      session = new Sessions.TranslateSession(
        data,
        screenToWorld(payload.point, data)
      )
    },
    updateTranslateSession(data, payload: PointerInfo) {
      session.update(data, screenToWorld(payload.point, data))
    },

    // Selection
    setPointedId(data, payload: PointerInfo) {
      data.pointedId = payload.target
    },
    clearPointedId(data) {
      data.pointedId = undefined
    },
    clearSelectedIds(data) {
      data.selectedIds.clear()
    },
    pullPointedIdFromSelectedIds(data) {
      const { selectedIds, pointedId } = data
      selectedIds.delete(pointedId)
    },
    pushPointedIdToSelectedIds(data) {
      data.selectedIds.add(data.pointedId)
    },
    // Camera
    zoomCamera(data, payload: { delta: number; point: number[] }) {
      const { camera } = data
      const p0 = screenToWorld(payload.point, data)
      camera.zoom = clamp(
        camera.zoom - (payload.delta / 100) * camera.zoom,
        0.5,
        3
      )
      const p1 = screenToWorld(payload.point, data)
      camera.point = vec.add(camera.point, vec.sub(p1, p0))

      document.documentElement.style.setProperty(
        "--camera-zoom",
        camera.zoom.toString()
      )
    },
    panCamera(data, payload: { delta: number[]; point: number[] }) {
      const { camera } = data
      data.camera.point = vec.sub(
        camera.point,
        vec.div(payload.delta, camera.zoom)
      )
    },
  },
  values: {
    selectedIds(data) {
      return new Set(data.selectedIds)
    },
    selectedBounds(data) {
      const {
        selectedIds,
        currentPageId,
        document: { pages },
      } = data

      return getCommonBounds(
        ...Array.from(selectedIds.values())
          .map((id) => {
            const shape = pages[currentPageId].shapes[id]

            switch (shape.type) {
              case ShapeType.Dot: {
                return Shapes[shape.type].getBounds(shape)
              }
              case ShapeType.Circle: {
                return Shapes[shape.type].getBounds(shape)
              }
              case ShapeType.Line: {
                return Shapes[shape.type].getBounds(shape)
              }
              case ShapeType.Polyline: {
                return Shapes[shape.type].getBounds(shape)
              }
              case ShapeType.Rectangle: {
                return Shapes[shape.type].getBounds(shape)
              }
              default: {
                return null
              }
            }
          })
          .filter(Boolean)
      )
    },
  },
})

let session: Sessions.BaseSession

export default state

export const useSelector = createSelectorHook(state)