/**
 * Type definitions for the declarative policy engine.
 *
 * Policies are plain data (JSON-serializable), deterministic, and
 * transport-agnostic — they operate on atproto accounts (DIDs), not raw blocks.
 */

// ============================================
// Target: which accounts a policy applies to
// ============================================

/** Match all serviced accounts. */
export interface TargetAll {
	type: "all";
}

/** Match an explicit list of DIDs. */
export interface TargetList {
	type: "list";
	dids: string[];
}

/** Match DIDs whose string representation matches a pattern (substring or prefix). */
export interface TargetPattern {
	type: "pattern";
	/** A prefix string to match against DIDs, e.g. "did:plc:" or "did:web:example.com". */
	prefix: string;
}

export type PolicyTarget = TargetAll | TargetList | TargetPattern;

// ============================================
// Replication goals
// ============================================

export interface ReplicationGoals {
	/** Minimum number of copies across peers (including this node). Default: 1. */
	minCopies: number;
	/** Preferred peer DIDs to replicate with. Optional. */
	preferredPeers?: string[];
}

// ============================================
// Sync configuration
// ============================================

export interface SyncConfig {
	/** How often to sync, in seconds. Default: 300 (5 minutes). */
	intervalSec: number;
}

// ============================================
// Retention configuration
// ============================================

export interface RetentionConfig {
	/** How long to keep data, in seconds. 0 = forever. Default: 0. */
	maxAgeSec: number;
	/** Whether to keep historical revisions. Default: false. */
	keepHistory: boolean;
}

// ============================================
// Policy definition
// ============================================

export interface Policy {
	/** Unique identifier for this policy. */
	id: string;
	/** Human-readable name. */
	name: string;
	/** Which accounts this policy applies to. */
	target: PolicyTarget;
	/** Replication goals. */
	replication: ReplicationGoals;
	/** Sync frequency. */
	sync: SyncConfig;
	/** Data retention. */
	retention: RetentionConfig;
	/** Priority (higher = more important). Range: 0-100. Default: 50. */
	priority: number;
	/** Whether this policy is currently active. */
	enabled: boolean;
}

// ============================================
// Effective policy: the resolved result for a single DID
// ============================================

/**
 * The effective (merged) policy for a single DID after evaluating
 * all matching policies.
 */
export interface EffectivePolicy {
	/** The DID this effective policy is for. */
	did: string;
	/** IDs of all policies that contributed to this result. */
	sourcePolicyIds: string[];
	/** Merged replication goals. */
	replication: ReplicationGoals;
	/** Merged sync config. */
	sync: SyncConfig;
	/** Merged retention config. */
	retention: RetentionConfig;
	/** Highest priority among matching policies. */
	priority: number;
	/** Whether replication is enabled (at least one enabled policy matches). */
	shouldReplicate: boolean;
}

// ============================================
// Policy set: what gets loaded from config / stored on disk
// ============================================

export interface PolicySet {
	/** Schema version for forward compatibility. */
	version: 1;
	/** All defined policies. */
	policies: Policy[];
}

// ============================================
// Defaults
// ============================================

export const DEFAULT_REPLICATION: ReplicationGoals = {
	minCopies: 1,
};

export const DEFAULT_SYNC: SyncConfig = {
	intervalSec: 300,
};

export const DEFAULT_RETENTION: RetentionConfig = {
	maxAgeSec: 0,
	keepHistory: false,
};

export const DEFAULT_PRIORITY = 50;

// ============================================
// Lifecycle types for persistent policies
// ============================================

/** Policy lifecycle state. */
export type PolicyState = "proposed" | "active" | "suspended" | "terminated" | "purged";

/** What kind of policy this is. */
export type PolicyType = "reciprocal" | "archive" | "config" | "saas" | "group";

/** How this policy was created. */
export type PolicySource = "config" | "file" | "offer" | "manual" | "api";

/** Consent status for the replication relationship. */
export type ConsentStatus = "reciprocal" | "consented" | "unconsented" | "revoked";

/**
 * A policy with lifecycle metadata for persistence.
 * Extends the base Policy with type, state, source, consent, and timestamps.
 */
export interface StoredPolicy extends Policy {
	/** What kind of policy this is. */
	type: PolicyType;
	/** Current lifecycle state. */
	state: PolicyState;
	/** How this policy was created. */
	source: PolicySource;
	/** Consent status. */
	consent: ConsentStatus;
	/** Who/what created this policy. */
	createdBy: string;
	/** The counterparty DID (for reciprocal/P2P policies). */
	counterpartyDid?: string;
	/** URI of the local offer record (for P2P policies). */
	localOfferUri?: string;
	/** URI of the remote offer record (for P2P policies). */
	remoteOfferUri?: string;
	/** When this policy was created. */
	createdAt: string;
	/** When this policy was activated. */
	activatedAt: string | null;
	/** When this policy was suspended. */
	suspendedAt: string | null;
	/** When this policy was terminated. */
	terminatedAt: string | null;
	/** When this policy expires (null = never). */
	expiresAt: string | null;
}

/**
 * Create a StoredPolicy from a base Policy with lifecycle metadata.
 * `type` is required (no inference from ID prefix).
 */
export function toStoredPolicy(
	policy: Policy,
	type: PolicyType,
	overrides?: Partial<Omit<StoredPolicy, keyof Policy | "type">>,
): StoredPolicy {
	const now = new Date().toISOString();
	return {
		...policy,
		type,
		state: overrides?.state ?? "active",
		source: overrides?.source ?? "manual",
		consent: overrides?.consent ?? "unconsented",
		createdBy: overrides?.createdBy ?? "system",
		counterpartyDid: overrides?.counterpartyDid,
		localOfferUri: overrides?.localOfferUri,
		remoteOfferUri: overrides?.remoteOfferUri,
		createdAt: overrides?.createdAt ?? now,
		activatedAt: overrides?.activatedAt ?? (overrides?.state === "active" || !overrides?.state ? now : null),
		suspendedAt: overrides?.suspendedAt ?? null,
		terminatedAt: overrides?.terminatedAt ?? null,
		expiresAt: overrides?.expiresAt ?? null,
	};
}