import * as React from 'react'
import { memo, type ReactNode } from 'react'
import { useTerminalSize } from '../../hooks/useTerminalSize.js'
import { stringWidth } from '../../ink/stringWidth.js'
import { Box, Text } from '../../ink.js'
import { truncatePathMiddle, truncateToWidth } from '../../utils/format.js'
import type { Theme } from '../../utils/theme.js'

export type SuggestionItem = {
  id: string
  displayText: string
  tag?: string
  description?: string
  metadata?: unknown
  color?: keyof Theme
}

export type SuggestionType =
  | 'command'
  | 'file'
  | 'directory'
  | 'agent'
  | 'shell'
  | 'custom-title'
  | 'slack-channel'
  | 'none'

export const OVERLAY_MAX_ITEMS = 5

/**
 * Get the icon for a suggestion based on its type
 * Icons: + for files, ◇ for MCP resources, * for agents
 */
function getIcon(itemId: string): string {
  if (itemId.startsWith('file-')) return '+'
  if (itemId.startsWith('mcp-resource-')) return '◇'
  if (itemId.startsWith('agent-')) return '*'
  return '+'
}

/**
 * Check if an item is a unified suggestion type (file, mcp-resource, or agent)
 */
function isUnifiedSuggestion(itemId: string): boolean {
  return (
    itemId.startsWith('file-') ||
    itemId.startsWith('mcp-resource-') ||
    itemId.startsWith('agent-')
  )
}

const SuggestionItemRow = memo(function SuggestionItemRow({
  item,
  maxColumnWidth,
  isSelected,
}: {
  item: SuggestionItem
  maxColumnWidth?: number
  isSelected: boolean
}): ReactNode {
  const columns = useTerminalSize().columns
  const isUnified = isUnifiedSuggestion(item.id)

  // For unified suggestions (file, mcp-resource, agent), use single-line layout with icon
  if (isUnified) {
    const icon = getIcon(item.id)
    const textColor: keyof Theme | undefined = isSelected
      ? 'suggestion'
      : undefined
    const dimColor = !isSelected

    const isFile = item.id.startsWith('file-')
    const isMcpResource = item.id.startsWith('mcp-resource-')

    // Calculate layout widths
    // Layout: "X " (2) + displayText + " – " (3) + description + padding (4)
    const iconWidth = 2 // icon + space (fixed)
    const paddingWidth = 4
    const separatorWidth = item.description ? 3 : 0 // ' – ' separator

    // For files, truncate middle of path to show both directory context and filename
    // For MCP resources, limit displayText to 30 chars (truncate from end)
    // For agents, no truncation
    let displayText: string
    if (isFile) {
      // Reserve space for description if present, otherwise use all available space
      const descReserve = item.description
        ? Math.min(20, stringWidth(item.description))
        : 0
      const maxPathLength =
        columns - iconWidth - paddingWidth - separatorWidth - descReserve
      displayText = truncatePathMiddle(item.displayText, maxPathLength)
    } else if (isMcpResource) {
      const maxDisplayTextLength = 30
      displayText = truncateToWidth(item.displayText, maxDisplayTextLength)
    } else {
      displayText = item.displayText
    }

    const availableWidth =
      columns -
      iconWidth -
      stringWidth(displayText) -
      separatorWidth -
      paddingWidth

    // Build the full line as a single string to prevent wrapping
    let lineContent: string
    if (item.description) {
      const maxDescLength = Math.max(0, availableWidth)
      const truncatedDesc = truncateToWidth(
        item.description.replace(/\s+/g, ' '),
        maxDescLength,
      )
      lineContent = `${icon} ${displayText} – ${truncatedDesc}`
    } else {
      lineContent = `${icon} ${displayText}`
    }

    return (
      <Text color={textColor} dimColor={dimColor} wrap="truncate">
        {lineContent}
      </Text>
    )
  }

  // For non-unified suggestions (commands, shell, etc.), use improved layout from main
  // Cap the command name column at 40% of terminal width to ensure description has space
  const maxNameWidth = Math.floor(columns * 0.4)
  const displayTextWidth = Math.min(
    maxColumnWidth ?? stringWidth(item.displayText) + 5,
    maxNameWidth,
  )

  const textColor = item.color || (isSelected ? 'suggestion' : undefined)
  const shouldDim = !isSelected

  // Truncate and pad the display text to fixed width
  let displayText = item.displayText
  if (stringWidth(displayText) > displayTextWidth - 2) {
    displayText = truncateToWidth(displayText, displayTextWidth - 2)
  }
  const paddedDisplayText =
    displayText +
    ' '.repeat(Math.max(0, displayTextWidth - stringWidth(displayText)))

  const tagText = item.tag ? `[${item.tag}] ` : ''
  const tagWidth = stringWidth(tagText)
  const descriptionWidth = Math.max(
    0,
    columns - displayTextWidth - tagWidth - 4,
  )
  // Skill descriptions can contain newlines (e.g. /claude-api's "TRIGGER
  // when:" block). A multi-line row grows the overlay past minHeight; when
  // the filter narrows past that skill, the overlay shrinks and leaves
  // ghost rows. Flatten to one line before truncating.
  const truncatedDescription = item.description
    ? truncateToWidth(item.description.replace(/\s+/g, ' '), descriptionWidth)
    : ''

  return (
    <Text wrap="truncate">
      <Text color={textColor} dimColor={shouldDim}>
        {paddedDisplayText}
      </Text>
      {tagText ? <Text dimColor>{tagText}</Text> : null}
      <Text
        color={isSelected ? 'suggestion' : undefined}
        dimColor={!isSelected}
      >
        {truncatedDescription}
      </Text>
    </Text>
  )
})

type Props = {
  suggestions: SuggestionItem[]
  selectedSuggestion: number
  maxColumnWidth?: number
  /**
   * When true, the suggestions are rendered inside a position=absolute
   * overlay. We omit minHeight and flex-end so the y-clamp in the
   * renderer doesn't push fewer items down into the prompt area.
   */
  overlay?: boolean
}

export function PromptInputFooterSuggestions({
  suggestions,
  selectedSuggestion,
  maxColumnWidth: maxColumnWidthProp,
  overlay,
}: Props): ReactNode {
  const { rows } = useTerminalSize()
  // Maximum number of suggestions to show at once (leaving space for prompt).
  // Overlay mode (fullscreen) uses a fixed 5 — the floating box sits over
  // the ScrollBox, so terminal height isn't the constraint.
  const maxVisibleItems = overlay
    ? OVERLAY_MAX_ITEMS
    : Math.min(6, Math.max(1, rows - 3))

  // No suggestions to display
  if (suggestions.length === 0) {
    return null
  }

  // Use prop if provided (stable width from all commands), otherwise calculate from visible
  const maxColumnWidth =
    maxColumnWidthProp ??
    Math.max(...suggestions.map(item => stringWidth(item.displayText))) + 5

  // Calculate visible items range based on selected index
  const startIndex = Math.max(
    0,
    Math.min(
      selectedSuggestion - Math.floor(maxVisibleItems / 2),
      suggestions.length - maxVisibleItems,
    ),
  )
  const endIndex = Math.min(startIndex + maxVisibleItems, suggestions.length)
  const visibleItems = suggestions.slice(startIndex, endIndex)

  // In non-overlay (inline) mode, justifyContent keeps suggestions
  // anchored to the bottom (near the prompt). In overlay mode we omit
  // both minHeight and flex-end: the parent is position=absolute with
  // bottom='100%', so its y is clamped to 0 by the renderer when it
  // would go negative. Adding minHeight + flex-end would create empty
  // padding rows that shift the visible items down into the prompt area
  // when the list has fewer items than maxVisibleItems.
  return (
    <Box
      flexDirection="column"
      justifyContent={overlay ? undefined : 'flex-end'}
    >
      {visibleItems.map(item => (
        <SuggestionItemRow
          key={item.id}
          item={item}
          maxColumnWidth={maxColumnWidth}
          isSelected={item.id === suggestions[selectedSuggestion]?.id}
        />
      ))}
    </Box>
  )
}

export default memo(PromptInputFooterSuggestions)