import {
  isPRReviewFromMetadata,
  isIssueWatchFromMetadata,
  issueFieldsFromMetadata,
} from "@/lib/metadata-utils";
import type { KanbanState, TaskDependencyRef } from "@/lib/state/slices/kanban/types";
import type {
  ForegroundActivity,
  TaskPendingAction,
  TaskOrigin,
  TaskPriority,
  TaskState,
  TaskSessionState,
} from "@/lib/types/http";
import type { TaskStatusSummary } from "@/lib/types/task-status-summary";

type KanbanTask = KanbanState["tasks"][number];

/**
 * Shape accepted by {@link toKanbanTask}. Satisfied by both the HTTP Task DTO
 * (which nests repositories) and the backend's `task.updated` WebSocket
 * payload (which flattens `repository_id` and uses `task_id`).
 *
 * The single publisher / single mapper design relies on this shape being the
 * contract; anyone changing what the backend emits needs to keep it in sync,
 * and the parity test in `map-task.test.ts` will catch drift.
 */
export type TaskLike = {
  id?: string;
  task_id?: string;
  workspace_id?: string;
  workflow_id?: string;
  workflow_step_id?: string;
  title?: string;
  description?: string | null;
  autopilot?: boolean;
  position?: number;
  state?: TaskState;
  priority?: TaskPriority;
  origin?: TaskOrigin | string | null;
  repositories?: Array<{
    id?: string;
    repository_id: string;
    base_branch?: string;
    checkout_branch?: string;
    branch_policy_id?: string;
    branch_policy_name?: string;
    branch_policy_base_branch?: string;
    branch_policy_branch_template?: string;
    branch_policy_pull_request_target?: string;
    position?: number;
  }>;
  workspace_folders?: Array<{
    id: string;
    local_path: string;
    display_name: string;
    position: number;
  }>;
  repository_id?: string;
  primary_session_id?: string | null;
  primary_session_state?: TaskSessionState | string | null;
  primary_session_pending_action?: TaskPendingAction | null;
  task_pending_action?: TaskPendingAction | null;
  /** True when the task's session was mid-turn when the backend died. */
  interrupted?: boolean;
  /** True when a workflow step's auto_start_agent on_enter action failed to
   *  launch a run for this task. */
  auto_start_failed?: boolean;
  foreground_activity?: ForegroundActivity | null;
  parked_on_background_work?: boolean;
  parked_revision?: number;
  parked_epoch?: number;
  active_subagent_count?: number;
  session_count?: number | null;
  review_status?: "pending" | "approved" | "changes_requested" | "rejected" | null;
  primary_executor_id?: string | null;
  primary_executor_profile_id?: string | null;
  primary_executor_type?: string | null;
  primary_executor_name?: string | null;
  primary_agent_name?: string | null;
  primary_agent_profile_id?: string | null;
  labels?: string | string[] | null;
  is_remote_executor?: boolean;
  parent_id?: string | null;
  assignee_user_id?: string;
  updated_at?: string;
  created_at?: string;
  wip_admitted?: boolean;
  queued_for_step_id?: string | null;
  queued_at?: string | null;
  blocked?: boolean;
  blocked_reason?: string | null;
  depends_on?: TaskDependencyRef[] | null;
  blocks?: TaskDependencyRef[] | null;
  start_when_unblocked?: boolean;
  metadata?: Record<string, unknown> | null;
  archived_at?: string | null;
  status_summary?: TaskStatusSummary | null;
  status_summary_invalidated?: boolean;
};

export type WorkspaceMode = "inherit_parent" | "new_workspace" | "shared_group";

export function workspaceModeFromMetadata(
  metadata: TaskLike["metadata"],
): WorkspaceMode | undefined {
  const workspace = metadata?.workspace;
  if (!workspace || typeof workspace !== "object") return undefined;
  const mode = (workspace as Record<string, unknown>).mode;
  if (mode === "inherit_parent" || mode === "new_workspace" || mode === "shared_group") {
    return mode;
  }
  return undefined;
}

function pickRepositoryId(source: TaskLike): string | undefined {
  return source.repository_id ?? source.repositories?.[0]?.repository_id ?? undefined;
}

function pickId(source: TaskLike): string {
  return (source.id ?? source.task_id ?? "") as string;
}

function pickLabels(source: TaskLike): string[] {
  if (Array.isArray(source.labels))
    return source.labels.filter((label) => typeof label === "string");
  if (!source.labels) return [];
  try {
    const decoded: unknown = JSON.parse(source.labels);
    return Array.isArray(decoded)
      ? decoded.filter((label): label is string => typeof label === "string")
      : [];
  } catch {
    return [];
  }
}

export function pickPendingAction(action: unknown): TaskPendingAction | null | undefined {
  if (action === null) return null;
  if (action === "clarification" || action === "permission") {
    return action;
  }
  return undefined;
}

function pickForegroundActivity(
  activity: TaskLike["foreground_activity"],
): ForegroundActivity | null | undefined {
  return activity === null ? null : (activity ?? undefined);
}

type KanbanTaskRepository = NonNullable<KanbanTask["repositories"]>[number];

function pickRepositories(source: TaskLike): KanbanTaskRepository[] | undefined {
  if (!source.repositories) return undefined;
  return source.repositories.map((r, idx) => ({
    id: r.id ?? "",
    repository_id: r.repository_id,
    base_branch: r.base_branch ?? "",
    checkout_branch: r.checkout_branch,
    branch_policy_id: r.branch_policy_id,
    branch_policy_name: r.branch_policy_name,
    branch_policy_base_branch: r.branch_policy_base_branch,
    branch_policy_branch_template: r.branch_policy_branch_template,
    branch_policy_pull_request_target: r.branch_policy_pull_request_target,
    position: r.position ?? idx,
  }));
}

function pickWorkspaceFolders(source: TaskLike): KanbanTask["workspaceFolders"] | undefined {
  return source.workspace_folders?.map((folder) => ({ ...folder }));
}

function primaryExecutorProjection(source: TaskLike) {
  return {
    primaryExecutorId: source.primary_executor_id ?? undefined,
    primaryExecutorProfileId: source.primary_executor_profile_id ?? undefined,
    primaryExecutorType: source.primary_executor_type ?? undefined,
    primaryExecutorName: source.primary_executor_name ?? undefined,
    isRemoteExecutor: source.is_remote_executor ?? false,
  };
}

/**
 * Build a canonical {@link KanbanTask} from either an HTTP DTO or a WebSocket
 * payload. Both paths share this helper so a single publisher change can never
 * leave them out of sync again (cf. sidebar filter regressions where the HTTP
 * snapshot derived `isPRReview` but the WS handler didn't).
 */
/**
 * dependencyProjection normalizes the derived dependency fields.
 *
 * A payload that carries NO dependency key at all leaves them undefined rather
 * than defaulting to "no edges". Most `task.updated` publishers are lightweight
 * and omit them, and inventing empty arrays here is destructive twice over: the
 * event can insert the task into the board store before boot hydration runs, and
 * hydration then keeps the "fresher" WS copy — permanently erasing the edges and
 * blanking the dependency chip. When the keys ARE present (every boot payload and
 * list read computes them), an empty list is a real "no edges".
 */
function dependencyProjection(
  source: TaskLike,
): Partial<
  Pick<KanbanTask, "blocked" | "blockedReason" | "dependsOn" | "blocks" | "startWhenUnblocked">
> {
  const mentionsDependencies =
    source.blocked !== undefined ||
    source.depends_on !== undefined ||
    source.blocks !== undefined ||
    source.start_when_unblocked !== undefined;
  if (!mentionsDependencies) return {};
  return {
    blocked: source.blocked ?? false,
    blockedReason: source.blocked_reason ?? undefined,
    dependsOn: source.depends_on ?? [],
    blocks: source.blocks ?? [],
    startWhenUnblocked: source.start_when_unblocked ?? false,
  };
}

/**
 * `primaryExecutorId`/`Name` map with `?? undefined`, so an omitted wire field
 * survives mapping as `undefined`. `isRemoteExecutor` maps with `?? false`
 * instead, so it can never signal omission on its own — but the backend only
 * ever emits `is_remote_executor` alongside `primary_executor_type` (both are
 * derived from the same executor snapshot), so gating the whole bundle on
 * `primaryExecutorType`'s own `undefined`-ness is the reliable signal.
 */
export function preserveOmittedExecutorFields(merged: KanbanTask, existing: KanbanTask): void {
  if (merged.primaryExecutorType !== undefined) return;
  copyPrimaryExecutorFields(merged, existing);
}

export function copyPrimaryExecutorFields(merged: KanbanTask, existing: KanbanTask): void {
  merged.primaryExecutorId = existing.primaryExecutorId;
  merged.primaryExecutorProfileId = existing.primaryExecutorProfileId;
  merged.primaryExecutorType = existing.primaryExecutorType;
  merged.primaryExecutorName = existing.primaryExecutorName;
  merged.isRemoteExecutor = existing.isRemoteExecutor;
}

/**
 * "Unassigned" has one spelling in the store: undefined.
 *
 * The wire uses an empty string for it (that is what a PATCH sends to
 * unassign), so without this the store would hold both "" and undefined for
 * the same state and every consumer would need to know that.
 */
export function pickAssignee(value: string | undefined): string | undefined {
  return value ? value : undefined;
}

// eslint-disable-next-line complexity -- Maps the complete task wire contract into the shared Kanban model.
export function toKanbanTask(source: TaskLike): KanbanTask {
  return {
    id: pickId(source),
    workspaceId: source.workspace_id,
    workflowId: source.workflow_id,
    workflowStepId: source.workflow_step_id ?? "",
    title: source.title ?? "",
    description: source.description ?? undefined,
    autopilot: source.autopilot,
    priority: source.priority,
    origin: source.origin,
    position: source.position ?? 0,
    state: source.state,
    repositoryId: pickRepositoryId(source),
    repositories: pickRepositories(source),
    workspaceFolders: pickWorkspaceFolders(source),
    primarySessionId: source.primary_session_id ?? undefined,
    primarySessionState: source.primary_session_state ?? undefined,
    primarySessionPendingAction: pickPendingAction(source.primary_session_pending_action),
    taskPendingAction: pickPendingAction(source.task_pending_action),
    interrupted: source.interrupted,
    autoStartFailed: source.auto_start_failed,
    foregroundActivity: pickForegroundActivity(source.foreground_activity),
    parkedOnBackgroundWork: source.parked_on_background_work,
    parkedRevision: source.parked_revision,
    parkedEpoch: source.parked_epoch,
    activeSubagentCount: source.active_subagent_count ?? undefined,
    sessionCount: source.session_count ?? undefined,
    reviewStatus: source.review_status ?? undefined,
    ...primaryExecutorProjection(source),
    primaryAgentProfileId: source.primary_agent_profile_id ?? undefined,
    primaryAgentName: source.primary_agent_name ?? undefined,
    labels: pickLabels(source),
    assigneeUserId: pickAssignee(source.assignee_user_id),
    parentTaskId: source.parent_id ?? undefined,
    workspaceMode: workspaceModeFromMetadata(source.metadata),
    updatedAt: source.updated_at,
    createdAt: source.created_at,
    wipAdmitted: source.wip_admitted,
    queuedForStepId: source.queued_for_step_id,
    queuedAt: source.queued_at,
    ...dependencyProjection(source),
    statusSummary: source.status_summary,
    metadata: source.metadata,
    isArchived: source.archived_at != null,
    isPRReview: isPRReviewFromMetadata(source.metadata),
    isIssueWatch: isIssueWatchFromMetadata(source.metadata),
    ...issueFieldsFromMetadata(source.metadata),
  } as KanbanTask;
}