import { type LonLatPoint } from '../../utils/projection'
import { type GameControl, type GameDefinition } from '../core/gameDefinition'
import { type GameEvent } from '../core/gameEvent'
import { type GameEffect, type GameResult } from '../core/gameResult'
import { type GameSessionState } from '../core/gameSessionState'
import { EMPTY_GAME_PRESENTATION_STATE, type GamePresentationState } from '../presentation/presentationState'
import { type RulePlugin } from './rulePlugin'

function getApproxDistanceMeters(a: LonLatPoint, b: LonLatPoint): number {
  const avgLatRad = ((a.lat + b.lat) / 2) * Math.PI / 180
  const dx = (b.lon - a.lon) * 111320 * Math.cos(avgLatRad)
  const dy = (b.lat - a.lat) * 110540
  return Math.sqrt(dx * dx + dy * dy)
}

function getScoringControls(definition: GameDefinition): GameControl[] {
  return definition.controls.filter((control) => control.kind === 'control')
}

function getSequentialTargets(definition: GameDefinition): GameControl[] {
  return definition.controls
}

function getCompletedControlSequences(definition: GameDefinition, state: GameSessionState): number[] {
  return getScoringControls(definition)
    .filter((control) => state.completedControlIds.includes(control.id) && typeof control.sequence === 'number')
    .map((control) => control.sequence as number)
}

function getCurrentTarget(definition: GameDefinition, state: GameSessionState): GameControl | null {
  return getSequentialTargets(definition).find((control) => control.id === state.currentTargetControlId) || null
}

function getCompletedLegIndices(definition: GameDefinition, state: GameSessionState): number[] {
  const targets = getSequentialTargets(definition)
  const completedLegIndices: number[] = []

  for (let index = 1; index < targets.length; index += 1) {
    if (state.completedControlIds.includes(targets[index].id)) {
      completedLegIndices.push(index - 1)
    }
  }

  return completedLegIndices
}

function getTargetText(control: GameControl): string {
  if (control.kind === 'start') {
    return '开始点'
  }

  if (control.kind === 'finish') {
    return '终点'
  }

  return '目标圈'
}


function buildPunchHintText(definition: GameDefinition, state: GameSessionState, currentTarget: GameControl | null): string {
  if (state.status === 'idle') {
    return '点击开始后先打开始点'
  }

  if (state.status === 'finished') {
    return '本局已完成'
  }

  if (!currentTarget) {
    return '本局已完成'
  }

  const targetText = getTargetText(currentTarget)
  if (state.inRangeControlId !== currentTarget.id) {
    return definition.punchPolicy === 'enter'
      ? `进入${targetText}自动打点`
      : `进入${targetText}后点击打点`
  }

  return definition.punchPolicy === 'enter'
    ? `${targetText}内，自动打点中`
    : `${targetText}内，可点击打点`
}

function buildPresentation(definition: GameDefinition, state: GameSessionState): GamePresentationState {
  const scoringControls = getScoringControls(definition)
  const sequentialTargets = getSequentialTargets(definition)
  const currentTarget = getCurrentTarget(definition, state)
  const currentTargetIndex = currentTarget ? sequentialTargets.findIndex((control) => control.id === currentTarget.id) : -1
  const completedControls = scoringControls.filter((control) => state.completedControlIds.includes(control.id))
  const running = state.status === 'running'
  const activeLegIndices = running && currentTargetIndex > 0
    ? [currentTargetIndex - 1]
    : []
  const completedLegIndices = getCompletedLegIndices(definition, state)
  const punchButtonEnabled = running && !!currentTarget && state.inRangeControlId === currentTarget.id && definition.punchPolicy === 'enter-confirm'
  const activeStart = running && !!currentTarget && currentTarget.kind === 'start'
  const completedStart = definition.controls.some((control) => control.kind === 'start' && state.completedControlIds.includes(control.id))
  const activeFinish = running && !!currentTarget && currentTarget.kind === 'finish'
  const completedFinish = definition.controls.some((control) => control.kind === 'finish' && state.completedControlIds.includes(control.id))
  const punchButtonText = currentTarget
    ? currentTarget.kind === 'start'
      ? '开始打卡'
      : currentTarget.kind === 'finish'
        ? '结束打卡'
        : '打点'
    : '打点'
  const revealFullCourse = completedStart

  if (!scoringControls.length) {
    return {
      ...EMPTY_GAME_PRESENTATION_STATE,
      activeStart,
      completedStart,
      activeFinish,
      completedFinish,
      revealFullCourse,
      activeLegIndices,
      completedLegIndices,
      progressText: '0/0',
      punchButtonText,
      punchableControlId: punchButtonEnabled && currentTarget ? currentTarget.id : null,
      punchButtonEnabled,
      punchHintText: buildPunchHintText(definition, state, currentTarget),
    }
  }

  return {
    activeControlIds: running && currentTarget ? [currentTarget.id] : [],
    activeControlSequences: running && currentTarget && currentTarget.kind === 'control' && typeof currentTarget.sequence === 'number' ? [currentTarget.sequence] : [],
    activeStart,
    completedStart,
    activeFinish,
    completedFinish,
    revealFullCourse,
    activeLegIndices,
    completedLegIndices,
    completedControlIds: completedControls.map((control) => control.id),
    completedControlSequences: getCompletedControlSequences(definition, state),
    progressText: `${completedControls.length}/${scoringControls.length}`,
    punchableControlId: punchButtonEnabled && currentTarget ? currentTarget.id : null,
    punchButtonEnabled,
    punchButtonText,
    punchHintText: buildPunchHintText(definition, state, currentTarget),
  }
}

function getInitialTargetId(definition: GameDefinition): string | null {
  const firstTarget = getSequentialTargets(definition)[0]
  return firstTarget ? firstTarget.id : null
}

function buildCompletedEffect(control: GameControl): GameEffect {
  if (control.kind === 'start') {
    return {
      type: 'control_completed',
      controlId: control.id,
      controlKind: 'start',
      sequence: null,
      label: control.label,
      displayTitle: '比赛开始',
      displayBody: '已完成开始点打卡，前往 1 号点。',
    }
  }

  if (control.kind === 'finish') {
    return {
      type: 'control_completed',
      controlId: control.id,
      controlKind: 'finish',
      sequence: null,
      label: control.label,
      displayTitle: '比赛结束',
      displayBody: '已完成终点打卡，本局结束。',
    }
  }

  const sequenceText = typeof control.sequence === 'number' ? String(control.sequence) : control.label
  const displayTitle = control.displayContent ? control.displayContent.title : `完成 ${sequenceText}`
  const displayBody = control.displayContent ? control.displayContent.body : control.label

  return {
    type: 'control_completed',
    controlId: control.id,
    controlKind: 'control',
    sequence: control.sequence,
    label: control.label,
    displayTitle,
    displayBody,
  }
}

function applyCompletion(definition: GameDefinition, state: GameSessionState, currentTarget: GameControl, at: number): GameResult {
  const targets = getSequentialTargets(definition)
  const currentIndex = targets.findIndex((control) => control.id === currentTarget.id)
  const completedControlIds = state.completedControlIds.includes(currentTarget.id)
    ? state.completedControlIds
    : [...state.completedControlIds, currentTarget.id]
  const nextTarget = currentIndex >= 0 && currentIndex < targets.length - 1
    ? targets[currentIndex + 1]
    : null
  const nextState: GameSessionState = {
    ...state,
    completedControlIds,
    currentTargetControlId: nextTarget ? nextTarget.id : null,
    inRangeControlId: null,
    score: getScoringControls(definition).filter((control) => completedControlIds.includes(control.id)).length,
    status: nextTarget || !definition.autoFinishOnLastControl ? state.status : 'finished',
    endedAt: nextTarget || !definition.autoFinishOnLastControl ? state.endedAt : at,
  }
  const effects: GameEffect[] = [buildCompletedEffect(currentTarget)]

  if (!nextTarget && definition.autoFinishOnLastControl) {
    effects.push({ type: 'session_finished' })
  }

  return {
    nextState,
    presentation: buildPresentation(definition, nextState),
    effects,
  }
}

export class ClassicSequentialRule implements RulePlugin {
  get mode(): 'classic-sequential' {
    return 'classic-sequential'
  }

  initialize(definition: GameDefinition): GameSessionState {
    return {
      status: 'idle',
      startedAt: null,
      endedAt: null,
      completedControlIds: [],
      currentTargetControlId: getInitialTargetId(definition),
      inRangeControlId: null,
      score: 0,
    }
  }

  buildPresentation(definition: GameDefinition, state: GameSessionState): GamePresentationState {
    return buildPresentation(definition, state)
  }

  reduce(definition: GameDefinition, state: GameSessionState, event: GameEvent): GameResult {
    if (event.type === 'session_started') {
      const nextState: GameSessionState = {
        ...state,
        status: 'running',
        startedAt: event.at,
        endedAt: null,
        inRangeControlId: null,
      }
      return {
        nextState,
        presentation: buildPresentation(definition, nextState),
        effects: [{ type: 'session_started' }],
      }
    }

    if (event.type === 'session_ended') {
      const nextState: GameSessionState = {
        ...state,
        status: 'finished',
        endedAt: event.at,
      }
      return {
        nextState,
        presentation: buildPresentation(definition, nextState),
        effects: [{ type: 'session_finished' }],
      }
    }

    if (state.status !== 'running' || !state.currentTargetControlId) {
      return {
        nextState: state,
        presentation: buildPresentation(definition, state),
        effects: [],
      }
    }

    const currentTarget = getCurrentTarget(definition, state)
    if (!currentTarget) {
      return {
        nextState: state,
        presentation: buildPresentation(definition, state),
        effects: [],
      }
    }

    if (event.type === 'gps_updated') {
      const distanceMeters = getApproxDistanceMeters(currentTarget.point, { lon: event.lon, lat: event.lat })
      const inRangeControlId = distanceMeters <= definition.punchRadiusMeters ? currentTarget.id : null
      const nextState: GameSessionState = {
        ...state,
        inRangeControlId,
      }

      if (definition.punchPolicy === 'enter' && inRangeControlId === currentTarget.id) {
        return applyCompletion(definition, nextState, currentTarget, event.at)
      }

      return {
        nextState,
        presentation: buildPresentation(definition, nextState),
        effects: [],
      }
    }

    if (event.type === 'punch_requested') {
      if (state.inRangeControlId !== currentTarget.id) {
        return {
          nextState: state,
          presentation: buildPresentation(definition, state),
          effects: [{ type: 'punch_feedback', text: currentTarget.kind === 'start' ? '未进入开始点打卡范围' : currentTarget.kind === 'finish' ? '未进入终点打卡范围' : '未进入目标打点范围', tone: 'warning' }],
        }
      }

      return applyCompletion(definition, state, currentTarget, event.at)
    }

    return {
      nextState: state,
      presentation: buildPresentation(definition, state),
      effects: [],
    }
  }
}