import type { Point, Rectangle } from '../../geometry'
import type {
  PortLabelLayoutCommonOptions,
  PortLabelLayoutDefinition,
} from './index'
import { toResult } from './util'

export interface InOutArgs extends PortLabelLayoutCommonOptions {
  offset?: number
}

export const outside: PortLabelLayoutDefinition<InOutArgs> = (
  portPosition,
  elemBBox,
  args,
) => outsideLayout(portPosition, elemBBox, false, args)

export const outsideOriented: PortLabelLayoutDefinition<InOutArgs> = (
  portPosition,
  elemBBox,
  args,
) => outsideLayout(portPosition, elemBBox, true, args)

export const inside: PortLabelLayoutDefinition<InOutArgs> = (
  portPosition,
  elemBBox,
  args,
) => insideLayout(portPosition, elemBBox, false, args)

export const insideOriented: PortLabelLayoutDefinition<InOutArgs> = (
  portPosition,
  elemBBox,
  args,
) => insideLayout(portPosition, elemBBox, true, args)

function outsideLayout(
  portPosition: Point,
  elemBBox: Rectangle,
  autoOrient: boolean,
  args: InOutArgs,
) {
  const offset = args.offset != null ? args.offset : 15
  const angle = elemBBox.getCenter().theta(portPosition)
  const bboxAngles = getBBoxAngles(elemBBox)

  let y
  let tx
  let ty
  let textAnchor
  let orientAngle = 0

  if (angle < bboxAngles[1] || angle > bboxAngles[2]) {
    y = '.3em'
    tx = offset
    ty = 0
    textAnchor = 'start'
  } else if (angle < bboxAngles[0]) {
    y = '0'
    tx = 0
    ty = -offset
    if (autoOrient) {
      orientAngle = -90
      textAnchor = 'start'
    } else {
      textAnchor = 'middle'
    }
  } else if (angle < bboxAngles[3]) {
    y = '.3em'
    tx = -offset
    ty = 0
    textAnchor = 'end'
  } else {
    y = '.6em'
    tx = 0
    ty = offset
    if (autoOrient) {
      orientAngle = 90
      textAnchor = 'start'
    } else {
      textAnchor = 'middle'
    }
  }

  return toResult(
    {
      position: {
        x: Math.round(tx),
        y: Math.round(ty),
      },
      angle: orientAngle,
      attrs: {
        '.': {
          y,
          'text-anchor': textAnchor,
        },
      },
    },
    args,
  )
}

function insideLayout(
  portPosition: Point,
  elemBBox: Rectangle,
  autoOrient: boolean,
  args: InOutArgs,
) {
  const offset = args.offset != null ? args.offset : 15
  const angle = elemBBox.getCenter().theta(portPosition)
  const bboxAngles = getBBoxAngles(elemBBox)

  let y
  let tx
  let ty
  let textAnchor
  let orientAngle = 0

  if (angle < bboxAngles[1] || angle > bboxAngles[2]) {
    y = '.3em'
    tx = -offset
    ty = 0
    textAnchor = 'end'
  } else if (angle < bboxAngles[0]) {
    y = '.6em'
    tx = 0
    ty = offset
    if (autoOrient) {
      orientAngle = 90
      textAnchor = 'start'
    } else {
      textAnchor = 'middle'
    }
  } else if (angle < bboxAngles[3]) {
    y = '.3em'
    tx = offset
    ty = 0
    textAnchor = 'start'
  } else {
    y = '0em'
    tx = 0
    ty = -offset
    if (autoOrient) {
      orientAngle = -90
      textAnchor = 'start'
    } else {
      textAnchor = 'middle'
    }
  }

  return toResult(
    {
      position: {
        x: Math.round(tx),
        y: Math.round(ty),
      },
      angle: orientAngle,
      attrs: {
        '.': {
          y,
          'text-anchor': textAnchor,
        },
      },
    },
    args,
  )
}

function getBBoxAngles(elemBBox: Rectangle) {
  const center = elemBBox.getCenter()

  const tl = center.theta(elemBBox.getTopLeft())
  const bl = center.theta(elemBBox.getBottomLeft())
  const br = center.theta(elemBBox.getBottomRight())
  const tr = center.theta(elemBBox.getTopRight())

  return [tl, tr, br, bl]
}