import { BLOCK_DIMENSIONS, CONTAINER_DIMENSIONS } from '@sim/workflow-renderer'
import {
  AUTO_LAYOUT_EXCLUDED_TYPES,
  CONTAINER_BLOCK_TYPES,
  CONTAINER_PADDING,
  CONTAINER_PADDING_X,
  CONTAINER_PADDING_Y,
  NOTE_BLOCK_TYPE,
  ROOT_PADDING_X,
  ROOT_PADDING_Y,
} from '@/lib/workflows/autolayout/constants'
import type { BlockMetrics, BoundingBox, Edge, GraphNode } from '@/lib/workflows/autolayout/types'
import { calculateWorkflowBlockDimensions } from '@/lib/workflows/blocks/deterministic-dimensions'
import { getConditionRows, getRouterRows } from '@/lib/workflows/dynamic-handle-topology'
import {
  buildCanonicalIndex,
  buildSubBlockValues,
  type CanonicalModeOverrides,
  evaluateSubBlockCondition,
  isSubBlockFeatureEnabled,
  isSubBlockHidden,
  isSubBlockVisibleForMode,
  isTriggerModeSubBlock,
} from '@/lib/workflows/subblocks/visibility'
import { getBlock } from '@/blocks'
import type { BlockState } from '@/stores/workflows/workflow/types'

/**
 * Resolves a potentially undefined numeric value to a fallback
 */
function resolveNumeric(value: number | undefined, fallback: number): number {
  return typeof value === 'number' && Number.isFinite(value) ? value : fallback
}

/**
 * Snaps a single coordinate value to the nearest grid position
 */
function snapToGrid(value: number, gridSize: number): number {
  return Math.round(value / gridSize) * gridSize
}

/**
 * Snaps a position to the nearest grid point.
 * Returns the original position if gridSize is 0 or not provided.
 */
export function snapPositionToGrid(
  position: { x: number; y: number },
  gridSize: number | undefined
): { x: number; y: number } {
  if (!gridSize || gridSize <= 0) {
    return position
  }
  return {
    x: snapToGrid(position.x, gridSize),
    y: snapToGrid(position.y, gridSize),
  }
}

/**
 * Snaps all node positions in a graph to grid positions and returns updated dimensions.
 * Returns null if gridSize is not set or no snapping was needed.
 */
export function snapNodesToGrid(
  nodes: Map<string, GraphNode>,
  gridSize: number | undefined
): { width: number; height: number } | null {
  if (!gridSize || gridSize <= 0 || nodes.size === 0) {
    return null
  }

  let minX = Number.POSITIVE_INFINITY
  let minY = Number.POSITIVE_INFINITY
  let maxX = Number.NEGATIVE_INFINITY
  let maxY = Number.NEGATIVE_INFINITY

  for (const node of nodes.values()) {
    node.position = snapPositionToGrid(node.position, gridSize)
    minX = Math.min(minX, node.position.x)
    minY = Math.min(minY, node.position.y)
    maxX = Math.max(maxX, node.position.x + node.metrics.width)
    maxY = Math.max(maxY, node.position.y + node.metrics.height)
  }

  return {
    width: maxX - minX + CONTAINER_PADDING * 2,
    height: maxY - minY + CONTAINER_PADDING * 2,
  }
}

/**
 * Checks if a block type is a container (loop or parallel)
 */
export function isContainerType(blockType: string): boolean {
  return CONTAINER_BLOCK_TYPES.has(blockType)
}

/**
 * Checks if a block should be excluded from autolayout
 */
export function shouldSkipAutoLayout(block?: BlockState): boolean {
  if (!block) return true
  return AUTO_LAYOUT_EXCLUDED_TYPES.has(block.type)
}

/**
 * Filters block IDs to only include those eligible for layout
 */
export function filterLayoutEligibleBlockIds(
  blockIds: string[],
  blocks: Record<string, BlockState>
): string[] {
  return blockIds.filter((id) => {
    const block = blocks[id]
    if (!block) return false
    return !shouldSkipAutoLayout(block)
  })
}

/**
 * Gets metrics for a container block
 */
function getContainerMetrics(block: BlockState): BlockMetrics {
  const measuredWidth = block.layout?.measuredWidth
  const measuredHeight = block.layout?.measuredHeight

  const containerWidth = Math.max(
    measuredWidth ?? 0,
    resolveNumeric(block.data?.width, CONTAINER_DIMENSIONS.DEFAULT_WIDTH)
  )
  const containerHeight = Math.max(
    measuredHeight ?? 0,
    resolveNumeric(block.data?.height, CONTAINER_DIMENSIONS.DEFAULT_HEIGHT)
  )

  return {
    width: containerWidth,
    height: containerHeight,
    minWidth: CONTAINER_DIMENSIONS.DEFAULT_WIDTH,
    minHeight: CONTAINER_DIMENSIONS.DEFAULT_HEIGHT,
    paddingTop: BLOCK_DIMENSIONS.HEADER_HEIGHT,
    paddingBottom: BLOCK_DIMENSIONS.HEADER_HEIGHT,
    paddingLeft: BLOCK_DIMENSIONS.HEADER_HEIGHT,
    paddingRight: BLOCK_DIMENSIONS.HEADER_HEIGHT,
  }
}

/**
 * Counts visible preview subblocks using the same visibility rules as the
 * workflow block preview when no DOM measurements are available.
 */
function getVisiblePreviewSubBlockCount(block: BlockState): number {
  const blockConfig = getBlock(block.type)
  if (!blockConfig?.subBlocks?.length) {
    return Object.values(block.subBlocks || {}).filter((subBlock) => subBlock != null).length
  }

  const rawValues = buildSubBlockValues(block.subBlocks || {})
  const canonicalModeOverrides =
    typeof block.data?.canonicalModes === 'object' && block.data.canonicalModes !== null
      ? (block.data.canonicalModes as CanonicalModeOverrides)
      : undefined

  if (canonicalModeOverrides) {
    rawValues.__canonicalModes = canonicalModeOverrides
  }

  const canonicalIndex = buildCanonicalIndex(blockConfig.subBlocks)
  const effectiveAdvanced = Boolean(block.advancedMode)
  const effectiveTrigger = Boolean(block.triggerMode)
  const isPureTriggerBlock = blockConfig.triggers?.enabled && blockConfig.category === 'triggers'

  return blockConfig.subBlocks.filter((subBlock) => {
    if (subBlock.hidden || subBlock.hideFromPreview) return false
    if (!isSubBlockFeatureEnabled(subBlock)) return false
    if (isSubBlockHidden(subBlock)) return false

    if (effectiveTrigger) {
      const isValidTriggerSubblock = isPureTriggerBlock
        ? isTriggerModeSubBlock(subBlock) || !subBlock.mode
        : isTriggerModeSubBlock(subBlock)

      if (!isValidTriggerSubblock) {
        return false
      }
    } else if (isTriggerModeSubBlock(subBlock)) {
      return false
    }

    if (
      !isSubBlockVisibleForMode(
        subBlock,
        effectiveAdvanced,
        canonicalIndex,
        rawValues,
        canonicalModeOverrides
      )
    ) {
      return false
    }

    if (!subBlock.condition) return true
    return evaluateSubBlockCondition(subBlock.condition, rawValues)
  }).length
}

/**
 * Estimates workflow block dimensions using the same deterministic row-based
 * formula used by the canvas block renderer.
 */
function estimateWorkflowBlockDimensions(block: BlockState): { width: number; height: number } {
  const blockConfig = getBlock(block.type)
  const visibleCount = getVisiblePreviewSubBlockCount(block)

  if (!blockConfig) {
    return {
      width: BLOCK_DIMENSIONS.FIXED_WIDTH,
      height: Math.max(
        BLOCK_DIMENSIONS.HEADER_HEIGHT +
          BLOCK_DIMENSIONS.WORKFLOW_CONTENT_PADDING +
          visibleCount * BLOCK_DIMENSIONS.WORKFLOW_ROW_HEIGHT,
        BLOCK_DIMENSIONS.MIN_HEIGHT
      ),
    }
  }

  return calculateWorkflowBlockDimensions({
    blockType: block.type,
    category: blockConfig.category,
    displayTriggerMode: Boolean(block.triggerMode),
    visibleSubBlockCount: visibleCount,
    conditionRowCount:
      block.type === 'condition'
        ? getConditionRows(block.id, block.subBlocks?.conditions?.value).length
        : 0,
    routerRowCount:
      block.type === 'router_v2'
        ? getRouterRows(block.id, block.subBlocks?.routes?.value).length
        : 0,
  })
}

/**
 * Gets metrics for a regular (non-container) block.
 * Falls back to subblock-based height estimation when no measurement exists,
 * which prevents overlaps for newly added blocks that haven't been rendered.
 */
function getRegularBlockMetrics(block: BlockState): BlockMetrics {
  const minWidth = BLOCK_DIMENSIONS.FIXED_WIDTH
  const minHeight = BLOCK_DIMENSIONS.MIN_HEIGHT
  const measuredH = block.layout?.measuredHeight ?? block.height
  const measuredW = block.layout?.measuredWidth
  const estimatedDimensions = estimateWorkflowBlockDimensions(block)
  const estimatedHeight = estimatedDimensions.height

  const hasMeasurement = typeof measuredH === 'number' && measuredH > 0
  const height = hasMeasurement ? Math.max(measuredH, estimatedHeight, minHeight) : estimatedHeight
  const width = Math.max(measuredW ?? estimatedDimensions.width, minWidth)

  return {
    width,
    height,
    minWidth,
    minHeight,
    paddingTop: BLOCK_DIMENSIONS.HEADER_HEIGHT,
    paddingBottom: BLOCK_DIMENSIONS.HEADER_HEIGHT,
    paddingLeft: BLOCK_DIMENSIONS.HEADER_HEIGHT,
    paddingRight: BLOCK_DIMENSIONS.HEADER_HEIGHT,
  }
}

/**
 * Gets the dimensions and metrics for a block
 */
export function getBlockMetrics(block: BlockState): BlockMetrics {
  if (isContainerType(block.type)) {
    return getContainerMetrics(block)
  }

  return getRegularBlockMetrics(block)
}

/**
 * Prepares metrics for all nodes in a graph
 */
export function prepareBlockMetrics(nodes: Map<string, GraphNode>): void {
  for (const node of nodes.values()) {
    node.metrics = getBlockMetrics(node.block)
  }
}

/**
 * Creates a bounding box from position and dimensions
 */
export function createBoundingBox(
  position: { x: number; y: number },
  dimensions: Pick<BlockMetrics, 'width' | 'height'>
): BoundingBox {
  return {
    x: position.x,
    y: position.y,
    width: dimensions.width,
    height: dimensions.height,
  }
}

/**
 * Checks if two bounding boxes overlap (with optional margin)
 */
export function boxesOverlap(box1: BoundingBox, box2: BoundingBox, margin = 0): boolean {
  return !(
    box1.x + box1.width + margin <= box2.x ||
    box2.x + box2.width + margin <= box1.x ||
    box1.y + box1.height + margin <= box2.y ||
    box2.y + box2.height + margin <= box1.y
  )
}

/**
 * Resolves the on-canvas dimensions of a note block.
 * Notes are fixed-width and use a deterministic height, but fall back to any
 * stored measurement or data override when present.
 */
function getNoteDimensions(block: BlockState): { width: number; height: number } {
  const width = Math.max(
    resolveNumeric(block.data?.width, 0),
    block.layout?.measuredWidth ?? 0,
    BLOCK_DIMENSIONS.FIXED_WIDTH
  )

  const defaultHeight =
    BLOCK_DIMENSIONS.HEADER_HEIGHT +
    BLOCK_DIMENSIONS.NOTE_CONTENT_PADDING +
    BLOCK_DIMENSIONS.NOTE_BASE_CONTENT_HEIGHT

  const height = Math.max(
    resolveNumeric(block.data?.height, 0),
    block.layout?.measuredHeight ?? 0,
    block.height ?? 0,
    defaultHeight
  )

  return { width, height }
}

/**
 * Checks if a block has a valid, finite position.
 * Returns false for missing, undefined, NaN, or Infinity coordinates.
 */
export function hasFinitePosition(block: BlockState): boolean {
  return Number.isFinite(block.position?.x) && Number.isFinite(block.position?.y)
}

/**
 * Determines whether a note and a block overlapped at their pre-layout
 * positions. Used by targeted layout to distinguish overlaps introduced by the
 * current pass from arrangements that already existed.
 */
function noteOverlappedBlockBefore(
  previousBlocks: Record<string, BlockState>,
  noteId: string,
  blockId: string
): boolean {
  const previousNote = previousBlocks[noteId]
  const previousBlock = previousBlocks[blockId]
  if (!previousNote || !previousBlock) return false

  // A block without a finite prior position was not yet placed on the canvas,
  // so it could not have overlapped anything before this pass.
  if (!hasFinitePosition(previousNote) || !hasFinitePosition(previousBlock)) return false

  // Derive dimensions from the prior blocks so a resize between passes does not
  // pair new dimensions with the old position.
  const noteBox = createBoundingBox(previousNote.position, getNoteDimensions(previousNote))
  const blockBox = createBoundingBox(previousBlock.position, getBlockMetrics(previousBlock))
  return boxesOverlap(blockBox, noteBox)
}

export interface ResolveNoteOverlapsOptions {
  /**
   * Pre-layout block snapshot. When provided, only notes whose overlap with a
   * block was *introduced* by the current pass are relocated (i.e. they overlap
   * now but did not at these positions). Targeted layout passes this so that
   * pre-existing note arrangements are preserved. When omitted (full
   * auto-layout), any note overlapping a block is relocated.
   */
  previousBlocks?: Record<string, BlockState>
}

/**
 * Relocates note blocks that overlap the laid-out workflow blocks.
 *
 * Notes are excluded from the topological layout because they are free-form
 * annotations, but repositioned workflow blocks can land on top of them. This
 * pass keeps notes that already sit in clear space and stacks any relocated
 * notes in a column beneath their parent group's blocks, preserving the notes'
 * relative reading order. Notes are grouped by parent so notes inside a
 * container are resolved against that container's children only.
 *
 * Placement is always computed against the full set of blocks and notes in the
 * group, so a relocated note never collides with anything regardless of which
 * overlaps triggered the relocation.
 */
export function resolveNoteOverlaps(
  blocks: Record<string, BlockState>,
  verticalSpacing: number,
  options: ResolveNoteOverlapsOptions = {}
): void {
  const { previousBlocks } = options
  const { root, children } = getBlocksByParent(blocks)
  const groups: string[][] = [root, ...Array.from(children.values())]

  for (const groupIds of groups) {
    const obstacles: Array<{ id: string; box: BoundingBox }> = []
    const noteIds: string[] = []
    let maxBottom = Number.NEGATIVE_INFINITY
    let minX = Number.POSITIVE_INFINITY

    for (const id of groupIds) {
      const block = blocks[id]
      // Skip non-finite positions so corrupted coordinates never propagate into
      // minX / maxBottom (and therefore into relocated note positions).
      if (!block || !hasFinitePosition(block)) continue

      if (block.type === NOTE_BLOCK_TYPE) {
        noteIds.push(id)
        const { height } = getNoteDimensions(block)
        maxBottom = Math.max(maxBottom, block.position.y + height)
        continue
      }

      if (shouldSkipAutoLayout(block)) continue

      const box = createBoundingBox(block.position, getBlockMetrics(block))
      obstacles.push({ id, box })
      maxBottom = Math.max(maxBottom, box.y + box.height)
      minX = Math.min(minX, box.x)
    }

    if (noteIds.length === 0 || obstacles.length === 0) continue

    noteIds.sort((a, b) => {
      const posA = blocks[a].position
      const posB = blocks[b].position
      return posA.y - posB.y || posA.x - posB.x
    })

    let stackY = maxBottom + verticalSpacing

    for (const id of noteIds) {
      const note = blocks[id]
      const dimensions = getNoteDimensions(note)
      const noteBox = createBoundingBox(note.position, dimensions)

      const needsRelocation = obstacles.some(({ id: blockId, box }) => {
        if (!boxesOverlap(box, noteBox)) return false
        if (previousBlocks) {
          return !noteOverlappedBlockBefore(previousBlocks, id, blockId)
        }
        return true
      })

      if (!needsRelocation) continue

      note.position = { x: minX, y: stackY }
      stackY += dimensions.height + verticalSpacing
    }
  }
}

/**
 * Groups blocks by their parent container
 */
export function getBlocksByParent(blocks: Record<string, BlockState>): {
  root: string[]
  children: Map<string, string[]>
} {
  const root: string[] = []
  const children = new Map<string, string[]>()

  for (const [id, block] of Object.entries(blocks)) {
    const parentId = block.data?.parentId

    if (!parentId) {
      root.push(id)
    } else {
      if (!children.has(parentId)) {
        children.set(parentId, [])
      }
      children.get(parentId)!.push(id)
    }
  }

  return { root, children }
}

/**
 * Normalizes node positions to start from a given padding offset.
 * Returns the bounding box dimensions of the normalized layout.
 */
export function normalizePositions(
  nodes: Map<string, GraphNode>,
  options: { isContainer: boolean }
): { width: number; height: number } {
  if (nodes.size === 0) {
    return { width: 0, height: 0 }
  }

  let minX = Number.POSITIVE_INFINITY
  let minY = Number.POSITIVE_INFINITY
  let maxX = Number.NEGATIVE_INFINITY
  let maxY = Number.NEGATIVE_INFINITY

  for (const node of nodes.values()) {
    minX = Math.min(minX, node.position.x)
    minY = Math.min(minY, node.position.y)
    maxX = Math.max(maxX, node.position.x + node.metrics.width)
    maxY = Math.max(maxY, node.position.y + node.metrics.height)
  }

  const paddingX = options.isContainer ? CONTAINER_PADDING_X : ROOT_PADDING_X
  const paddingY = options.isContainer ? CONTAINER_PADDING_Y : ROOT_PADDING_Y

  const xOffset = paddingX - minX
  const yOffset = paddingY - minY

  for (const node of nodes.values()) {
    node.position = {
      x: node.position.x + xOffset,
      y: node.position.y + yOffset,
    }
  }

  const width = maxX - minX + CONTAINER_PADDING * 2
  const height = maxY - minY + CONTAINER_PADDING * 2

  return { width, height }
}

/**
 * Transfers block height measurements from source blocks to target blocks.
 * Matches blocks by type:name key.
 */
export function transferBlockHeights(
  sourceBlocks: Record<string, BlockState>,
  targetBlocks: Record<string, BlockState>
): void {
  // Build a map of block type+name to heights from source
  const heightMap = new Map<string, { height: number; width: number }>()

  for (const block of Object.values(sourceBlocks)) {
    const key = `${block.type}:${block.name}`
    heightMap.set(key, {
      height: block.height || BLOCK_DIMENSIONS.MIN_HEIGHT,
      width: block.layout?.measuredWidth || BLOCK_DIMENSIONS.FIXED_WIDTH,
    })
  }

  // Transfer heights to target blocks
  for (const block of Object.values(targetBlocks)) {
    const key = `${block.type}:${block.name}`
    const measurements = heightMap.get(key)

    if (measurements) {
      block.height = measurements.height

      if (!block.layout) {
        block.layout = {}
      }
      block.layout.measuredHeight = measurements.height
      block.layout.measuredWidth = measurements.width
    }
  }
}

/**
 * Calculates the internal depth (max layer count) for each subflow container.
 * Used to properly position blocks that connect after a subflow ends.
 *
 * @param blocks - All blocks in the workflow
 * @param edges - All edges in the workflow
 * @param assignLayersFn - Function to assign layers to blocks
 * @returns Map of container block IDs to their internal layer depth
 */
export function calculateSubflowDepths(
  blocks: Record<string, BlockState>,
  edges: Edge[],
  assignLayersFn: (blocks: Record<string, BlockState>, edges: Edge[]) => Map<string, GraphNode>
): Map<string, number> {
  const depths = new Map<string, number>()
  const { children } = getBlocksByParent(blocks)

  for (const [containerId, childIds] of children.entries()) {
    if (childIds.length === 0) {
      depths.set(containerId, 1)
      continue
    }

    const childBlocks: Record<string, BlockState> = {}
    const layoutChildIds = filterLayoutEligibleBlockIds(childIds, blocks)
    for (const childId of layoutChildIds) {
      childBlocks[childId] = blocks[childId]
    }

    const childEdges = edges.filter(
      (edge) => layoutChildIds.includes(edge.source) && layoutChildIds.includes(edge.target)
    )

    if (Object.keys(childBlocks).length === 0) {
      depths.set(containerId, 1)
      continue
    }

    const childNodes = assignLayersFn(childBlocks, childEdges)
    let maxLayer = 0
    for (const node of childNodes.values()) {
      maxLayer = Math.max(maxLayer, node.layer)
    }

    depths.set(containerId, Math.max(maxLayer + 1, 1))
  }

  return depths
}

/**
 * Layout function type for preparing container dimensions.
 * Returns laid out nodes and bounding dimensions.
 */
export type LayoutFunction = (
  blocks: Record<string, BlockState>,
  edges: Edge[],
  options: {
    isContainer: boolean
    layoutOptions?: {
      horizontalSpacing?: number
      verticalSpacing?: number
      padding?: { x: number; y: number }
      gridSize?: number
    }
    subflowDepths?: Map<string, number>
  }
) => { nodes: Map<string, GraphNode>; dimensions: { width: number; height: number } }

/**
 * Pre-calculates container dimensions by laying out their children.
 * Processes containers bottom-up to handle nested subflows correctly.
 * This ensures accurate width/height values before root-level layout.
 *
 * @param blocks - All blocks in the workflow (will be mutated with updated dimensions)
 * @param edges - All edges in the workflow
 * @param layoutFn - The layout function to use for calculating dimensions
 * @param horizontalSpacing - Horizontal spacing between blocks
 * @param verticalSpacing - Vertical spacing between blocks
 * @param gridSize - Optional grid size for snap-to-grid
 */
export function prepareContainerDimensions(
  blocks: Record<string, BlockState>,
  edges: Edge[],
  layoutFn: LayoutFunction,
  horizontalSpacing: number,
  verticalSpacing: number,
  gridSize?: number
): void {
  const { children } = getBlocksByParent(blocks)

  // Build dependency graph to process nested containers bottom-up
  const containerIds = Array.from(children.keys())
  const containerDepth = new Map<string, number>()

  // Calculate nesting depth for each container
  for (const containerId of containerIds) {
    let depth = 0
    let currentId: string | undefined = containerId
    while (currentId) {
      const block: BlockState | undefined = blocks[currentId]
      const parentId: string | undefined = block?.data?.parentId
      currentId = parentId
      if (currentId) depth++
    }
    containerDepth.set(containerId, depth)
  }

  // Sort containers by depth (deepest first) for bottom-up processing
  const sortedContainerIds = containerIds.sort((a, b) => {
    const depthA = containerDepth.get(a) ?? 0
    const depthB = containerDepth.get(b) ?? 0
    return depthB - depthA
  })

  // Process each container, laying out its children to determine dimensions
  for (const containerId of sortedContainerIds) {
    const container = blocks[containerId]
    if (!container) continue

    const childIds = children.get(containerId) ?? []
    const layoutChildIds = filterLayoutEligibleBlockIds(childIds, blocks)

    if (layoutChildIds.length === 0) {
      // Empty container - use default dimensions
      container.data = {
        ...container.data,
        width: CONTAINER_DIMENSIONS.DEFAULT_WIDTH,
        height: CONTAINER_DIMENSIONS.DEFAULT_HEIGHT,
      }
      container.layout = {
        ...container.layout,
        measuredWidth: CONTAINER_DIMENSIONS.DEFAULT_WIDTH,
        measuredHeight: CONTAINER_DIMENSIONS.DEFAULT_HEIGHT,
      }
      continue
    }

    // Build subset of blocks and edges for this container's children
    const childBlocks: Record<string, BlockState> = {}
    for (const childId of layoutChildIds) {
      childBlocks[childId] = blocks[childId]
    }

    const childEdges = edges.filter(
      (edge) => layoutChildIds.includes(edge.source) && layoutChildIds.includes(edge.target)
    )

    // Layout children to get dimensions
    const { dimensions } = layoutFn(childBlocks, childEdges, {
      isContainer: true,
      layoutOptions: {
        horizontalSpacing: horizontalSpacing * 0.85,
        verticalSpacing,
        gridSize,
      },
    })

    // Update container with calculated dimensions
    const calculatedWidth = Math.max(dimensions.width, CONTAINER_DIMENSIONS.DEFAULT_WIDTH)
    const calculatedHeight = Math.max(dimensions.height, CONTAINER_DIMENSIONS.DEFAULT_HEIGHT)

    container.data = {
      ...container.data,
      width: calculatedWidth,
      height: calculatedHeight,
    }
    container.layout = {
      ...container.layout,
      measuredWidth: calculatedWidth,
      measuredHeight: calculatedHeight,
    }
  }
}