/**
 * 原子模型的后台接口：分组树 + 卡片。
 *
 * 分组是唯一容器，卡片只是「勾选分组」的展示组合；两者都通过业务键关联。
 */
export type GroupFormat = 'apps' | 'posters' | 'articles'

export type GroupEntry = {
  id: string
  format?: GroupFormat
  name?: string
  title?: string
  href?: string
  description?: string
  desc?: string
}

export type GroupNode = {
  key: string
  parentKey?: string | null
  title: string
  icon: string
  barColor: string
  previewLimit?: number | null
  sort: number
  /** 是否启用；禁用后前台不展示 */
  enabled: boolean
  entries: GroupEntry[]
  children: GroupNode[]
}

export type CardGroupRef = {
  groupKey: string
  previewLimit?: number | null
}

export type CardItem = {
  id: number
  key: string
  title: string
  sort: number
  groups: CardGroupRef[]
}

export type ManageData = {
  groups: GroupNode[]
  cards: CardItem[]
}

export type SimpleResult = { ok: true } | { ok: false; error: string }

async function errorMessage(response: Response, fallback: string): Promise<string> {
  const payload = (await response.json().catch(() => null)) as { error?: string } | null
  return payload?.error ?? `${fallback}（${response.status}）`
}

export async function fetchManage(): Promise<ManageData> {
  try {
    const response = await fetch('/api/catalog2', { credentials: 'same-origin' })
    if (!response.ok) return { groups: [], cards: [] }
    return (await response.json()) as ManageData
  } catch {
    return { groups: [], cards: [] }
  }
}

export async function createNode(input: {
  key: string
  title: string
  parentKey?: string
  format?: GroupFormat
  icon?: string
  sort?: number
  enabled?: boolean
}): Promise<SimpleResult> {
  try {
    const response = await fetch('/api/nodes', {
      method: 'POST',
      credentials: 'same-origin',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify(input),
    })
    return response.ok ? { ok: true } : { ok: false, error: await errorMessage(response, '创建失败') }
  } catch (error) {
    return { ok: false, error: error instanceof Error ? error.message : '网络错误' }
  }
}

export async function updateNode(
  key: string,
  patch: {
    title?: string
    parentKey?: string
    sort?: number
    format?: GroupFormat
    icon?: string
    enabled?: boolean
  },
): Promise<SimpleResult> {
  try {
    const response = await fetch(`/api/nodes/${encodeURIComponent(key)}`, {
      method: 'PATCH',
      credentials: 'same-origin',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify(patch),
    })
    return response.ok ? { ok: true } : { ok: false, error: await errorMessage(response, '保存失败') }
  } catch (error) {
    return { ok: false, error: error instanceof Error ? error.message : '网络错误' }
  }
}

export async function deleteNode(key: string): Promise<SimpleResult> {
  try {
    const response = await fetch(`/api/nodes/${encodeURIComponent(key)}`, {
      method: 'DELETE',
      credentials: 'same-origin',
    })
    return response.ok ? { ok: true } : { ok: false, error: await errorMessage(response, '删除失败') }
  } catch (error) {
    return { ok: false, error: error instanceof Error ? error.message : '网络错误' }
  }
}

export async function createCard(title: string): Promise<{ ok: true; id: number } | { ok: false; error: string }> {
  try {
    const response = await fetch('/api/cards', {
      method: 'POST',
      credentials: 'same-origin',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify({ title }),
    })
    if (!response.ok) return { ok: false, error: await errorMessage(response, '创建失败') }
    const payload = (await response.json()) as { id: number }
    return { ok: true, id: payload.id }
  } catch (error) {
    return { ok: false, error: error instanceof Error ? error.message : '网络错误' }
  }
}

export async function updateCard(
  id: number,
  patch: { title?: string; sort?: number },
): Promise<SimpleResult> {
  try {
    const response = await fetch(`/api/cards/${id}`, {
      method: 'PATCH',
      credentials: 'same-origin',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify(patch),
    })
    return response.ok ? { ok: true } : { ok: false, error: await errorMessage(response, '保存失败') }
  } catch (error) {
    return { ok: false, error: error instanceof Error ? error.message : '网络错误' }
  }
}

export async function deleteCard(id: number): Promise<SimpleResult> {
  try {
    const response = await fetch(`/api/cards/${id}`, {
      method: 'DELETE',
      credentials: 'same-origin',
    })
    return response.ok ? { ok: true } : { ok: false, error: await errorMessage(response, '删除失败') }
  } catch (error) {
    return { ok: false, error: error instanceof Error ? error.message : '网络错误' }
  }
}

export async function setCardGroups(
  id: number,
  groups: CardGroupRef[],
): Promise<SimpleResult> {
  try {
    const response = await fetch(`/api/cards/${id}/groups`, {
      method: 'PUT',
      credentials: 'same-origin',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify(groups),
    })
    return response.ok ? { ok: true } : { ok: false, error: await errorMessage(response, '保存失败') }
  } catch (error) {
    return { ok: false, error: error instanceof Error ? error.message : '网络错误' }
  }
}

/** 把分组树拍平成下拉选项 */
export function flattenGroups(
  groups: GroupNode[],
  depth = 0,
): { key: string; title: string; depth: number; enabled: boolean }[] {
  return groups.flatMap((group) => [
    {
      key: group.key,
      title: group.title,
      depth,
      enabled: group.enabled !== false,
    },
    ...flattenGroups(group.children, depth + 1),
  ])
}