import { GameState, SaveMeta, SnapshotMeta, Id } from '../types/domain'
import { validateLoadedState, exportEnvelope, parseImportEnvelope } from './migrate'

const GAME_VERSION = '0.1.41'

const DB_PREFIX = 'cotyc-save-'
let seqCounter = 0

export interface SaveDbDriver {
  open(name: string): Promise<void>
  close(): Promise<void>
  run(sql: string, params?: unknown[]): Promise<unknown>
  all<T>(sql: string, params?: unknown[]): Promise<T[]>
  exec(sql: string): Promise<unknown>
}

export interface TableDef {
  name: string
  cols: Record<string, string>
}

export class SaveSlot {
  constructor(
    public slot: number,
    private driver: SaveDbDriver
  ) {}

  private get name(): string {
    return `${DB_PREFIX}${this.slot}`
  }

  async open(): Promise<void> {
    await this.driver.open(this.name)
    await this.ensureSchema()
  }

  private async ensureSchema(): Promise<void> {
    const driver = this.driver
    await driver.exec(`CREATE TABLE IF NOT EXISTS meta (key string PRIMARY KEY, value string)`)
    await driver.exec(`CREATE TABLE IF NOT EXISTS snapshot (id string PRIMARY KEY, year number, month number, savedAt string, label string, data string)`)
  }

  async saveState(state: GameState, label: string): Promise<string> {
    const id = `${state.year}.${state.month}.${Date.now().toString(36)}-${(seqCounter++ % 1296).toString(36)}`
    const json = JSON.stringify(state)
    await this.driver.run(
      `INSERT INTO snapshot (id, year, month, savedAt, label, data) VALUES (?, ?, ?, ?, ?, ?)`,
      [id, state.year, state.month, new Date().toISOString(), label, json]
    )
    // 0.1.38 P1-F：回读校验——确认数据真正落盘
    const verify = await this.driver.all<{ data: string }>(
      `SELECT data FROM snapshot WHERE id = ?`,
      [id]
    )
    if (!verify.length || !verify[0]!.data) {
      throw new Error(`存档写入校验失败：数据未落盘（slot=${this.slot}, id=${id}）`)
    }
    // 校验 JSON 可解析且关键字段在
    try {
      const check = JSON.parse(verify[0]!.data) as GameState
      if (!check.family || !check.members || typeof check.seed !== 'string') {
        throw new Error('存档回读校验失败：关键字段缺失')
      }
    } catch (e) {
      throw new Error(`存档回读校验失败：${String(e).slice(0, 80)}`)
    }
    const keep = 12
    const rows = await this.driver.all<{ id: string }>(
      `SELECT id FROM snapshot ORDER BY year DESC, month DESC, savedAt DESC`
    )
    if (rows.length > keep) {
      const drop = rows.slice(keep).map((r) => r.id)
      for (const d of drop) {
        await this.driver.run(`DELETE FROM snapshot WHERE id = ?`, [d])
      }
    }
    return id
  }

  async listSnapshots(): Promise<SnapshotMeta[]> {
    const rows = await this.driver.all<SnapshotMeta & { data?: string }>(`SELECT id, year, month, savedAt, label FROM snapshot ORDER BY year DESC, month DESC`)
    return rows.map((r) => ({ id: r.id, year: r.year, month: r.month, savedAt: r.savedAt, label: r.label }))
  }

  async loadState(id?: string): Promise<GameState | null> {
    const rows = await this.driver.all<{ data: string }>(
      id
        ? `SELECT data FROM snapshot WHERE id = ?`
        : `SELECT data FROM snapshot ORDER BY year DESC, month DESC, savedAt DESC LIMIT 1`,
      id ? [id] : []
    )
    if (!rows || rows.length === 0) return null
    const state = JSON.parse(rows[0]!.data) as GameState
    const r = validateLoadedState(state)
    if (!r.ok) throw new Error(r.message)
    return r.state
  }

  async deleteSnapshot(id: string): Promise<void> {
    await this.driver.run(`DELETE FROM snapshot WHERE id = ?`, [id])
  }

  async getMeta(): Promise<SaveMeta | null> {
    const rows = await this.driver.all<{ value: string }>(`SELECT value FROM meta WHERE key = 'meta'`)
    if (!rows || rows.length === 0) return null
    return JSON.parse(rows[0].value) as SaveMeta
  }

  async setMeta(meta: SaveMeta): Promise<void> {
    const exists = await this.driver.all<{ key: string }>(`SELECT key FROM meta WHERE key = 'meta'`)
    const json = JSON.stringify(meta)
    if (exists.length > 0) {
      await this.driver.run(`UPDATE meta SET value = ? WHERE key = 'meta'`, [json])
    } else {
      await this.driver.run(`INSERT INTO meta (key, value) VALUES (?, ?)`, ['meta', json])
    }
  }

  async exportAll(): Promise<string> {
    const state = await this.loadState()
    if (!state) throw new Error('无可导出存档')
    const meta = await this.getMeta()
    const envelope = JSON.parse(exportEnvelope(state)) as { payload: GameState }
    return JSON.stringify({ app: 'cotyc', meta, payload: envelope.payload })
  }

  async importAll(data: string): Promise<boolean> {
    try {
      const parsed = parseImportEnvelope(data)
      if (!parsed.ok) return false
      const state = parsed.state
      await this.driver.exec(`DELETE FROM snapshot`)
      await this.driver.exec(`DELETE FROM meta`)
      await this.saveState(state, 'import')
      const aliveCount = Object.values(state.members).filter((c) => c.alive).length
      await this.setMeta(buildSimpleMeta(state, this.slot, aliveCount))
      return true
    } catch {
      return false
    }
  }

  async wipe(): Promise<void> {
    await this.driver.exec(`DELETE FROM snapshot`)
    await this.driver.exec(`DELETE FROM meta`)
    await this.driver.exec(`DELETE FROM chronicle`)
  }
}

export function buildSimpleMeta(state: GameState, slot: number, memberCount: number): SaveMeta {
  return {
    slot,
    surname: state.family.surname,
    name: state.family.name,
    estate: state.family.estate,
    year: state.year,
    month: state.month,
    generation: state.family.generation,
    members: memberCount,
    reputation: state.family.reputation,
    updatedAt: new Date().toISOString(),
    version: GAME_VERSION
  }
}

export function saveNameOf(meta: SaveMeta | null): string {
  if (!meta) return ''
  return `${meta.name} · ${meta.estate}`
}