defmodule Linear.Queries do
  @moduledoc false

  alias Linear.{Client, Pagination}

  @viewer_query """
  query LinearViewer {
    viewer { id name email displayName active admin }
  }
  """

  @teams_query """
  query LinearTeams {
    teams { nodes { id name key description } }
  }
  """

  @issue_query """
  query LinearIssue($id: String!) {
    issue(id: $id) {
      id identifier title description priority url branchName
      state { id name }
      assignee { id name email }
      labels { nodes { id name color } }
      project { id name }
      team { id name key }
      createdAt updatedAt
    }
  }
  """

  @issues_query """
  query LinearIssues($filter: IssueFilter, $first: Int!, $after: String, $includeArchived: Boolean) {
    issues(filter: $filter, first: $first, after: $after, includeArchived: $includeArchived) {
      nodes {
        id identifier title description priority url branchName
        state { id name }
        assignee { id name email }
        labels { nodes { id name color } }
        project { id name }
        team { id name key }
        createdAt updatedAt
      }
      pageInfo { hasNextPage endCursor }
    }
  }
  """

  @workflow_states_query """
  query LinearWorkflowStates($filter: WorkflowStateFilter) {
    workflowStates(filter: $filter) {
      nodes { id name color type position
        team { id name key }
      }
    }
  }
  """

  @projects_query """
  query LinearProjects($first: Int!, $after: String, $includeArchived: Boolean) {
    projects(first: $first, after: $after, includeArchived: $includeArchived) {
      nodes {
        id name description state url
        teams { nodes { id name key } }
        createdAt updatedAt
      }
      pageInfo { hasNextPage endCursor }
    }
  }
  """

  @spec viewer(Client.t(), keyword()) :: {:ok, map()} | {:error, term()}
  def viewer(client, opts \\ []) do
    case Client.query(client, @viewer_query, opts) do
      {:ok, %{"viewer" => viewer}} -> {:ok, viewer}
      error -> error
    end
  end

  @spec list_teams(Client.t(), keyword()) :: {:ok, [map()]} | {:error, term()}
  def list_teams(client, opts \\ []) do
    case Client.query(client, @teams_query, opts) do
      {:ok, %{"teams" => %{"nodes" => nodes}}} -> {:ok, nodes}
      error -> error
    end
  end

  @spec get_issue(Client.t(), String.t(), keyword()) :: {:ok, map()} | {:error, term()}
  def get_issue(client, issue_id, opts \\ []) do
    case Client.query(client, @issue_query, Keyword.merge(opts, variables: %{"id" => issue_id})) do
      {:ok, %{"issue" => issue}} -> {:ok, issue}
      error -> error
    end
  end

  @spec list_issues(Client.t(), keyword()) :: {:ok, [map()]} | {:error, term()}
  def list_issues(client, opts \\ []) do
    first = Keyword.get(opts, :first, 50)
    include_archived = Keyword.get(opts, :include_archived, false)
    filter = build_issue_filter(opts)
    query_opts = Keyword.take(opts, [:request_fn])

    Pagination.paginate(fn after_cursor ->
      variables =
        %{"filter" => filter, "first" => first, "includeArchived" => include_archived}
        |> put_cursor(after_cursor)

      case Client.query(client, @issues_query, Keyword.merge(query_opts, variables: variables)) do
        {:ok, %{"issues" => connection}} -> {:ok, connection}
        error -> error
      end
    end)
  end

  @spec list_workflow_states(Client.t(), keyword()) :: {:ok, [map()]} | {:error, term()}
  def list_workflow_states(client, opts \\ []) do
    filter =
      case Keyword.get(opts, :team_id) do
        nil -> nil
        id -> %{"team" => %{"id" => %{"eq" => id}}}
      end

    variables = if filter, do: %{"filter" => filter}, else: %{}
    query_opts = Keyword.take(opts, [:request_fn])

    case Client.query(client, @workflow_states_query, Keyword.merge(query_opts, variables: variables)) do
      {:ok, %{"workflowStates" => %{"nodes" => nodes}}} -> {:ok, nodes}
      error -> error
    end
  end

  @spec list_projects(Client.t(), keyword()) :: {:ok, [map()]} | {:error, term()}
  def list_projects(client, opts \\ []) do
    first = Keyword.get(opts, :first, 50)
    include_archived = Keyword.get(opts, :include_archived, false)
    query_opts = Keyword.take(opts, [:request_fn])

    Pagination.paginate(fn after_cursor ->
      variables =
        %{"first" => first, "includeArchived" => include_archived}
        |> put_cursor(after_cursor)

      case Client.query(client, @projects_query, Keyword.merge(query_opts, variables: variables)) do
        {:ok, %{"projects" => connection}} -> {:ok, connection}
        error -> error
      end
    end)
  end

  defp build_issue_filter(opts) do
    %{}
    |> maybe_filter(:team_id, opts, fn id -> %{"team" => %{"id" => %{"eq" => id}}} end)
    |> maybe_filter(:project_id, opts, fn id -> %{"project" => %{"id" => %{"eq" => id}}} end)
    |> maybe_filter(:state_names, opts, fn names -> %{"state" => %{"name" => %{"in" => names}}} end)
    |> maybe_filter(:assignee_id, opts, fn id -> %{"assignee" => %{"id" => %{"eq" => id}}} end)
    |> then(fn f -> if f == %{}, do: nil, else: f end)
  end

  defp maybe_filter(filter, key, opts, build_fn) do
    case Keyword.get(opts, key) do
      nil -> filter
      [] -> filter
      value -> Map.merge(filter, build_fn.(value))
    end
  end

  defp put_cursor(variables, nil), do: variables
  defp put_cursor(variables, cursor), do: Map.put(variables, "after", cursor)
end