defmodule BearCli.Api do
  @moduledoc """
  Bear 伺服器 HTTP 介面（一律使用 `Req`）。

  - `GET /userinfo`：PAT 模式身分驗證（issue #6）。
  - App 管理 API `/api/v1/apps`（alterminal/bear#28；PAT Bearer、admin 限定）。
  - 個人自助 API `/api/v1/profile*`（alterminal/bear#35；PAT Bearer、
    任何有效帳號）：profile／密碼／email／sessions／PAT／MFA。
  - 管理端 API `/api/v1/jwks`/`/api/v1/accounts`/`/api/v1/audit-logs`
    (alterminal/bear#36; PAT Bearer, admin only).
  """

  @finch BearCli.Finch

  @doc """
  呼叫 `GET {issuer}/userinfo`（Bearer token）。

  回傳：
    - `{:ok, claims}` — 200，claims 為 JSON map
    - `{:error, :unauthorized, description}` — 401
    - `{:error, :server_error, status}` — 其他非 2xx
    - `{:error, :network, reason}` — 傳輸層錯誤
  """
  def userinfo(issuer, token) do
    url = String.trim_trailing(issuer, "/") <> "/userinfo"

    case Req.get(url,
           headers: [authorization: "Bearer " <> token, accept: "application/json"],
           retry: false,
           finch: [name: @finch]
         ) do
      {:ok, %Req.Response{status: 200, body: body}} ->
        {:ok, decode_body(body)}

      {:ok, %Req.Response{status: 401, body: body}} ->
        {:error, :unauthorized, error_description(body)}

      {:ok, %Req.Response{status: status}} ->
        {:error, :server_error, status}

      {:error, exception} ->
        {:error, :network, Exception.message(exception)}
    end
  end

  defp decode_body(%{} = body), do: body
  defp decode_body(body) when is_binary(body), do: Jason.decode!(body)
  defp decode_body(_), do: %{}

  defp error_description(body) when is_binary(body) do
    case Jason.decode(body) do
      {:ok, %{"error_description" => desc}} when is_binary(desc) -> desc
      {:ok, %{"error" => err}} when is_binary(err) -> err
      _ -> "invalid_token"
    end
  end

  defp error_description(_), do: "invalid_token"

  # -- App 管理 API（alterminal/bear#28；PAT Bearer、admin 限定）--

  @doc """
  `GET /api/v1/apps`：列出 App（分頁）。

  `params` 為 keyword（`page:`／`per_page:`，可加 `visibility:`／`status:` 過濾）。
  成功回 `{:ok, %{"data" => [apps], "page" => n, "per_page" => n, "total" => n}}`。
  """
  def apps_list(issuer, token, params \\ []) do
    api_request(issuer, token, :get, "/api/v1/apps", params: params)
  end

  @doc "`GET /api/v1/apps/{id}`：單一 App（`client_secret` 永不回傳）。"
  def apps_get(issuer, token, id) do
    api_request(issuer, token, :get, "/api/v1/apps/" <> URI.encode(id))
  end

  @doc """
  `POST /api/v1/apps`：建立 App。`method=client_secret` 且未給
  `client_secret` 時由伺服器產生，成功回應內含一次性明文
  （`%{"data" => app, "client_secret" => secret}`）。
  """
  def apps_create(issuer, token, attrs) do
    api_request(issuer, token, :post, "/api/v1/apps", json: attrs)
  end

  @doc "`PUT /api/v1/apps/{id}`：部分更新（只送有給的欄位）。"
  def apps_update(issuer, token, id, attrs) do
    api_request(issuer, token, :put, "/api/v1/apps/" <> URI.encode(id), json: attrs)
  end

  @doc """
  `POST /api/v1/apps/{id}/rotate-secret`：輪轉 client secret，回應內含
  一次性明文。PKCE App 回 422 `%{"error" => "pkce_app"}`。
  """
  def apps_rotate_secret(issuer, token, id) do
    api_request(issuer, token, :post, "/api/v1/apps/" <> URI.encode(id) <> "/rotate-secret",
      json: %{}
    )
  end

  @doc "`POST /api/v1/apps/{id}/toggle`：切換 active ↔ inactive。"
  def apps_toggle(issuer, token, id) do
    api_request(issuer, token, :post, "/api/v1/apps/" <> URI.encode(id) <> "/toggle", json: %{})
  end

  # -- 個人自助 API（alterminal/bear#35；PAT Bearer、任何有效帳號）--

  @doc "`GET /api/v1/profile`：完整個人資料（含 MFA 狀態）。"
  def profile_get(issuer, token) do
    api_request(issuer, token, :get, "/api/v1/profile")
  end

  @doc "`PUT /api/v1/profile`：更新個人資料欄位（只送有給的欄位）。"
  def profile_update(issuer, token, attrs) do
    api_request(issuer, token, :put, "/api/v1/profile", json: attrs)
  end

  @doc """
  `POST /api/v1/profile/password`：變更密碼（body：`current_password`、
  `new_password`、`password_confirmation`；伺服器驗舊密碼，不因 CLI 放寬）。
  """
  def profile_change_password(issuer, token, current_password, new_password) do
    api_request(issuer, token, :post, "/api/v1/profile/password",
      json: %{
        current_password: current_password,
        new_password: new_password,
        password_confirmation: new_password
      }
    )
  end

  @doc "`POST /api/v1/profile/email/request-codes`：寄發 email 變更雙向驗證碼。"
  def profile_email_request_codes(issuer, token, new_email) do
    api_request(issuer, token, :post, "/api/v1/profile/email/request-codes",
      json: %{new_email: new_email}
    )
  end

  @doc """
  `POST /api/v1/profile/email`：確認變更 email（body：`new_email`、
  `current_code`、`new_code`）。
  """
  def profile_email_change(issuer, token, new_email, current_code, new_code) do
    api_request(issuer, token, :post, "/api/v1/profile/email",
      json: %{new_email: new_email, current_code: current_code, new_code: new_code}
    )
  end

  @doc "`GET /api/v1/profile/sessions`：列出作用中 session（新到舊）。"
  def sessions_list(issuer, token) do
    api_request(issuer, token, :get, "/api/v1/profile/sessions")
  end

  @doc "`POST /api/v1/profile/sessions/{id}/revoke`：撤銷單一 session。"
  def sessions_revoke(issuer, token, id) do
    api_request(issuer, token, :post, "/api/v1/profile/sessions/" <> URI.encode(id) <> "/revoke",
      json: %{}
    )
  end

  @doc """
  `POST /api/v1/profile/sessions/revoke-others`：撤銷其他 session
  （body `keep` 可省略＝全部撤銷）。
  """
  def sessions_revoke_others(issuer, token, keep \\ nil) do
    api_request(issuer, token, :post, "/api/v1/profile/sessions/revoke-others",
      json: %{keep: keep} |> Map.reject(fn {_k, v} -> is_nil(v) end)
    )
  end

  @doc "`GET /api/v1/profile/tokens`：列出未撤銷的 PAT（新到舊）。"
  def tokens_list(issuer, token) do
    api_request(issuer, token, :get, "/api/v1/profile/tokens")
  end

  @doc """
  `POST /api/v1/profile/tokens`：建立 PAT；明文 `token` 只在成功回應
  出現一次（body：`name`、`expires_in`＝天數或 `never`）。
  """
  def tokens_create(issuer, token, name, expires_in) do
    api_request(issuer, token, :post, "/api/v1/profile/tokens",
      json: %{name: name, expires_in: expires_in}
    )
  end

  @doc "`POST /api/v1/profile/tokens/{id}/revoke`：撤銷單一 PAT。"
  def tokens_revoke(issuer, token, id) do
    api_request(issuer, token, :post, "/api/v1/profile/tokens/" <> URI.encode(id) <> "/revoke",
      json: %{}
    )
  end

  @doc """
  `POST /api/v1/profile/mfa/setup`（無 body）：開始 TOTP 設定，回
  `%{"data" => %{"secret" => ..., "otpauth_uri" => ...}}`。已啟用 MFA 回
  422 `already_enabled`。
  """
  def mfa_setup(issuer, token) do
    api_request(issuer, token, :post, "/api/v1/profile/mfa/setup", json: %{})
  end

  @doc """
  `POST /api/v1/profile/mfa/setup/confirm`（body：`code`）：確認設定並
  啟用 MFA，回一次性 recovery codes。
  """
  def mfa_setup_confirm(issuer, token, code) do
    api_request(issuer, token, :post, "/api/v1/profile/mfa/setup/confirm", json: %{code: code})
  end

  @doc """
  `POST /api/v1/profile/mfa/disable`（body：`code`＝目前 TOTP 或
  recovery code）：停用 MFA。
  """
  def mfa_disable(issuer, token, code) do
    api_request(issuer, token, :post, "/api/v1/profile/mfa/disable", json: %{code: code})
  end

  @doc """
  `POST /api/v1/profile/mfa/recovery-codes`（body：`code`）：重產一組
  一次性 recovery codes（舊組全部失效）。
  """
  def mfa_recovery_codes(issuer, token, code) do
    api_request(issuer, token, :post, "/api/v1/profile/mfa/recovery-codes", json: %{code: code})
  end

  # -- 共用請求輔助 --

  # 回傳：
  #   {:ok, body} | {:error, :unauthorized, desc} | {:error, :forbidden, desc}
  #   | {:error, :not_found, desc} | {:error, :unprocessable_entity, body}
  #   | {:error, :too_many_requests, body}
  #   | {:error, :server_error, status} | {:error, :network, reason}
  defp api_request(issuer, token, method, path, extra \\ []) do
    url = String.trim_trailing(issuer, "/") <> path

    opts =
      [
        headers: [authorization: "Bearer " <> token, accept: "application/json"],
        retry: false,
        finch: [name: @finch]
      ]
      |> Keyword.merge(extra)

    case apply(Req, method, [url, opts]) do
      {:ok, %Req.Response{status: status, body: body}} when status in 200..299 ->
        {:ok, decode_body(body)}

      {:ok, %Req.Response{status: 401, body: body}} ->
        {:error, :unauthorized, error_description(decode_body(body))}

      {:ok, %Req.Response{status: 403, body: body}} ->
        {:error, :forbidden, error_description(decode_body(body))}

      {:ok, %Req.Response{status: 404, body: body}} ->
        {:error, :not_found, error_description(decode_body(body))}

      {:ok, %Req.Response{status: 422, body: body}} ->
        {:error, :unprocessable_entity, decode_body(body)}

      {:ok, %Req.Response{status: 429, body: body}} ->
        {:error, :too_many_requests, decode_body(body)}

      {:ok, %Req.Response{status: status}} ->
        {:error, :server_error, status}

      {:error, exception} ->
        {:error, :network, Exception.message(exception)}
    end
  end

  @doc "`GET /api/v1/jwks`: list all keys (active and inactive), newest first (no pagination)."
  def jwks_list(issuer, token) do
    api_request(issuer, token, :get, "/api/v1/jwks")
  end

  @doc """
  `POST /api/v1/jwks`: create a new signing key. attrs: `%{"kid" => "...", "alg" => "RS256"}`
  (`alg` optional; RS256/384/512, ES256/384/512). Key material is never serialized.
  """
  def jwks_create(issuer, token, attrs) do
    api_request(issuer, token, :post, "/api/v1/jwks", json: attrs)
  end

  @doc "`GET /api/v1/jwks/{id}`: single key (public metadata only)."
  def jwks_get(issuer, token, id) do
    api_request(issuer, token, :get, "/api/v1/jwks/" <> URI.encode(id))
  end

  @doc "`POST /api/v1/jwks/{id}/toggle`: switch key between active and inactive."
  def jwks_toggle(issuer, token, id) do
    api_request(issuer, token, :post, "/api/v1/jwks/" <> URI.encode(id) <> "/toggle", json: %{})
  end

  # -- Accounts API (alterminal/bear#46; PAT Bearer, admin only) --

  @doc """
  `GET /api/v1/accounts`: paginated list (newest first; per_page max 100).
  Returns `{:ok, %{"data" => [accounts], "page" => n, "per_page" => n, "total" => n}}`.
  """
  def accounts_list(issuer, token, params \\ []) do
    api_request(issuer, token, :get, "/api/v1/accounts", params: params)
  end

  @doc """
  `POST /api/v1/accounts`: create an account directly (no email verification).
  attrs: `%{"email" => "...", "hash_password" => "<plaintext>", "role" => "user|admin"}`
  (`role` optional, default `user`).
  """
  def accounts_create(issuer, token, attrs) do
    api_request(issuer, token, :post, "/api/v1/accounts", json: attrs)
  end

  @doc "`GET /api/v1/accounts/{id}`: single account (no credential fields)."
  def accounts_get(issuer, token, id) do
    api_request(issuer, token, :get, "/api/v1/accounts/" <> URI.encode(id))
  end

  @doc """
  `PUT /api/v1/accounts/{id}`: update role; attrs: `%{"role" => "user|admin"}`.
  """
  def accounts_update_role(issuer, token, id, attrs) do
    api_request(issuer, token, :put, "/api/v1/accounts/" <> URI.encode(id), json: attrs)
  end

  @doc """
  `PUT /api/v1/accounts/{id}/password`: admin sets a new password (no old password
  needed); attrs: `%{"hash_password" => "<plaintext>"}`.
  """
  def accounts_set_password(issuer, token, id, attrs) do
    api_request(issuer, token, :put, "/api/v1/accounts/" <> URI.encode(id) <> "/password",
      json: attrs
    )
  end

  @doc "`DELETE /api/v1/accounts/{id}`: hard-delete an account (admin path). Returns `{:ok, %{}}` (204 empty)."
  def accounts_delete(issuer, token, id) do
    api_request(issuer, token, :delete, "/api/v1/accounts/" <> URI.encode(id))
  end

  # -- Audit logs API (alterminal/bear#46; PAT Bearer, admin only) --

  @doc """
  `GET /api/v1/audit-logs`: paginated list (newest first). params: `page:` /
  `per_page:` (max 200) / `category:` filter. Returns `{:ok, %{"data" => [entries],
  "page" => n, "per_page" => n, "total" => n, "total_pages" => n,
  "emails" => %{id => email}}}`.
  """
  def audit_logs_list(issuer, token, params \\ []) do
    api_request(issuer, token, :get, "/api/v1/audit-logs", params: params)
  end
end