import { randomUUID } from 'crypto'
import type { OutlineItem, OutlineStatus } from '../../../shared/types'
import type { SqliteDb } from '../types'

function mapRow(row: Record<string, unknown>): OutlineItem {
  return {
    id: row.id as string,
    parentId: (row.parent_id as string | null) ?? null,
    title: row.title as string,
    description: (row.description as string) ?? '',
    status: row.status as OutlineStatus,
    expectedWordCount: (row.expected_word_count as number | null) ?? null,
    chapterId: (row.chapter_id as string | null) ?? null,
    sortOrder: row.sort_order as number,
    createdAt: row.created_at as string,
    updatedAt: row.updated_at as string
  }
}

function buildTree(items: OutlineItem[]): OutlineItem[] {
  const byParent = new Map<string | null, OutlineItem[]>()
  for (const item of items) {
    const key = item.parentId
    if (!byParent.has(key)) byParent.set(key, [])
    byParent.get(key)!.push({ ...item, children: [] })
  }
  const attach = (parentId: string | null): OutlineItem[] => {
    const nodes = byParent.get(parentId) ?? []
    nodes.sort((a, b) => a.sortOrder - b.sortOrder)
    for (const node of nodes) {
      node.children = attach(node.id)
    }
    return nodes
  }
  return attach(null)
}

export class OutlineRepository {
  constructor(private db: SqliteDb) {}

  create(parentId: string | null, title: string, sortOrder: number): OutlineItem {
    const id = randomUUID()
    this.db
      .prepare(
        `INSERT INTO outline_items (id, parent_id, title, sort_order)
         VALUES (?, ?, ?, ?)`
      )
      .run(id, parentId, title, sortOrder)
    return this.get(id)!
  }

  get(id: string): OutlineItem | null {
    const row = this.db.prepare('SELECT * FROM outline_items WHERE id = ?').get(id) as
      | Record<string, unknown>
      | undefined
    return row ? mapRow(row) : null
  }

  listFlat(): OutlineItem[] {
    return (
      this.db.prepare('SELECT * FROM outline_items ORDER BY sort_order').all() as Record<string, unknown>[]
    ).map(mapRow)
  }

  listTree(): OutlineItem[] {
    return buildTree(this.listFlat())
  }

  update(
    id: string,
    patch: Partial<{
      title: string
      description: string
      status: OutlineStatus
      expectedWordCount: number | null
      chapterId: string | null
      sortOrder: number
    }>
  ): OutlineItem {
    const existing = this.get(id)
    if (!existing) throw new Error('Outline item not found')

    this.db
      .prepare(
        `UPDATE outline_items SET
          title = ?, description = ?, status = ?,
          expected_word_count = ?, chapter_id = ?, sort_order = ?,
          updated_at = datetime('now')
         WHERE id = ?`
      )
      .run(
        patch.title ?? existing.title,
        patch.description ?? existing.description,
        patch.status ?? existing.status,
        patch.expectedWordCount !== undefined ? patch.expectedWordCount : existing.expectedWordCount,
        patch.chapterId !== undefined ? patch.chapterId : existing.chapterId,
        patch.sortOrder ?? existing.sortOrder,
        id
      )
    return this.get(id)!
  }

  delete(id: string): void {
    this.db.prepare('DELETE FROM outline_items WHERE id = ?').run(id)
  }

  move(id: string, parentId: string | null, sortOrder: number): OutlineItem {
    const existing = this.get(id)
    if (!existing) throw new Error('Outline item not found')

    this.db
      .prepare(
        `UPDATE outline_items SET parent_id = ?, sort_order = ?, updated_at = datetime('now') WHERE id = ?`
      )
      .run(parentId, sortOrder, id)
    return this.get(id)!
  }

  listUncovered(): OutlineItem[] {
    return (
      this.db
        .prepare('SELECT * FROM outline_items WHERE chapter_id IS NULL ORDER BY sort_order')
        .all() as Record<string, unknown>[]
    ).map(mapRow)
  }

  nextSortOrder(parentId: string | null): number {
    const row = parentId
      ? (this.db
          .prepare('SELECT MAX(sort_order) AS maxOrder FROM outline_items WHERE parent_id = ?')
          .get(parentId) as { maxOrder: number | null })
      : (this.db
          .prepare('SELECT MAX(sort_order) AS maxOrder FROM outline_items WHERE parent_id IS NULL')
          .get() as { maxOrder: number | null })
    return (row?.maxOrder ?? -1) + 1
  }
}