/// <reference path="./ambient-modules.d.ts" />
import * as path from 'node:path'
import { matchesKey } from '@earendil-works/pi-tui'
import type { UndoOperation } from './reverse-last-state.ts'

type PickerContext = {
  cwd: string
  hasUI: boolean
  ui: {
    setWidget?: (key: string, content: string[] | undefined) => void
    onTerminalInput?: (
      handler: (data: string) => { consume?: boolean; data?: string } | undefined
    ) => () => void
  }
}

function formatCandidateLabel(cwd: string, operation: UndoOperation): string {
  const stamp = new Date(operation.timestamp).toLocaleTimeString('en-GB', {
    hour: '2-digit',
    minute: '2-digit',
    second: '2-digit',
    hour12: false
  })
  const sample = operation.files
    .slice(0, 2)
    .map((file) => pathRelative(cwd, file.absPath))
    .join(', ')
  const suffix = operation.files.length > 2 ? ` +${operation.files.length - 2} more` : ''
  return `${stamp} ${operation.toolName} (${operation.files.length} file${operation.files.length === 1 ? '' : 's'}) ${sample}${suffix}`
}

function pathRelative(cwd: string, absPath: string): string {
  return path.relative(cwd, absPath) || absPath
}

export async function selectOperationsFromUI(
  ctx: PickerContext,
  operations: UndoOperation[]
): Promise<Set<string> | undefined> {
  const setWidget = ctx.ui.setWidget
  const onTerminalInput = ctx.ui.onTerminalInput
  if (!ctx.hasUI || !setWidget || !onTerminalInput) {
    return undefined
  }

  const widgetKey = 'undo-picker'
  const selected = operations.map(() => false)
  let cursor = 0

  return new Promise((resolve) => {
    const render = () => {
      const lines = [
        'Select changes to reverse (since last user message).',
        'Space toggle • a select all/none • Enter apply • Esc cancel',
        '',
        ...operations.map(
          (operation, index) =>
            `${index === cursor ? '>' : ' '} ${selected[index] ? '[x]' : '[ ]'} ${formatCandidateLabel(ctx.cwd, operation)}`
        )
      ]
      setWidget(widgetKey, lines)
    }

    const finish = (value: Set<string> | undefined) => {
      unsubscribe()
      setWidget(widgetKey, undefined)
      resolve(value)
    }

    render()
    const unsubscribe = onTerminalInput((data) => {
      if (matchesKey(data, 'escape') || matchesKey(data, 'ctrl+c')) {
        finish(undefined)
        return { consume: true }
      }
      if (matchesKey(data, 'enter') || matchesKey(data, 'return')) {
        const ids = new Set<string>()
        for (let index = 0; index < operations.length; index++) {
          if (selected[index]) {
            ids.add(operations[index].id)
          }
        }
        finish(ids)
        return { consume: true }
      }
      if (data === ' ') {
        selected[cursor] = !selected[cursor]
        render()
        return { consume: true }
      }
      if (data === 'a' || data === 'A') {
        const allSelected = selected.every(Boolean)
        for (let index = 0; index < selected.length; index++) {
          selected[index] = !allSelected
        }
        render()
        return { consume: true }
      }
      if (matchesKey(data, 'up') || data === 'k') {
        cursor = cursor > 0 ? cursor - 1 : operations.length - 1
        render()
        return { consume: true }
      }
      if (matchesKey(data, 'down') || data === 'j') {
        cursor = cursor < operations.length - 1 ? cursor + 1 : 0
        render()
        return { consume: true }
      }
      return undefined
    })
  })
}