/**
 * Routine notification policies, semantic delta evaluation,
 * deterministic content hashing, and quiet suppression rules.
 *
 * Implements Feature F8 per PROJECT.md and ORIGINAL_REQUEST.md.
 */

export type RoutineNotifyMode = "always" | "on_change" | "on_failure" | "never";

export interface RoutineDeltaEvaluation {
  /** True when current output substantively differs from previous output. */
  hasChanged: boolean;
  /** Concise, human-readable summary of what changed (under 120 chars). */
  deltaSummary?: string;
  /** Deterministic content hash of the current normalized output. */
  changeHash: string;
}

export interface NormalizationOptions {
  /**
   * Keys to ignore during normalization (e.g. volatile timestamps, ephemeral IDs).
   * Default includes: ["durationMs", "timestamp", "runId", "attemptId", "executionId",
   *                    "messageId", "taskId", "createdAt", "updatedAt", "nonce"]
   */
  ignoreKeys?: readonly string[];

  /**
   * Normalizes whitespace in string values (trims outer whitespace, normalizes CRLF).
   * Default: true
   */
  normalizeWhitespace?: boolean;

  /**
   * Number of decimal places to round floating point numbers to avoid IEEE-754 epsilon noise.
   * Default: 6
   */
  numericPrecision?: number;

  /**
   * Sorts arrays of primitive values (strings/numbers) when order is non-semantic.
   * Default: false
   */
  sortArraysOfPrimitives?: boolean;
}

export interface DeltaEvaluationOptions extends NormalizationOptions {
  /** Maximum character length of the generated delta summary. Default: 120 */
  maxSummaryLength?: number;
}

export type RoutineSuppressReason =
  | "unchanged"
  | "never_mode"
  | "success_in_failure_mode"
  | "disabled"
  | "empty_output";

export type RoutineEarconCue =
  | "routine_changed"
  | "routine_failure"
  | "routine_completed_quiet"
  | null;

export interface RoutineNotificationDecision {
  /** Whether a user-visible notification (push, toast, badge) should be dispatched. */
  shouldNotify: boolean;

  /** Rationale when notification was suppressed. */
  suppressReason?: RoutineSuppressReason;

  /** Whether substantive output change occurred. */
  hasChanged: boolean;

  /** Normalized hash of the current output. */
  changeHash: string;

  /** Hash of the previous output if available. */
  prevHash?: string;

  /** Human-readable delta summary if changed. */
  deltaSummary?: string;

  /** Associated tactile sound cue from Feature F4. */
  earconCue: RoutineEarconCue;

  /** Whether the chat thread should be marked unread. */
  markUnread: boolean;

  /** True when execution completed in quiet background mode without user-facing interruptions. */
  quiet: boolean;

  /** Pre-built notification payload when shouldNotify is true. */
  notificationPayload?: {
    kind: "completion" | "failure";
    title: string;
    body: string;
  };
}

export interface RoutineNotificationPolicy {
  /** Configured notification policy mode. */
  notifyMode: RoutineNotifyMode;

  /**
   * Evaluates delta between two content hashes.
   * Conforms directly to PROJECT.md line 88 interface contract.
   */
  evaluateDelta(prevOutputHash: string, currentOutputHash: string): boolean;

  /**
   * Evaluates substantive delta between previous and current execution outputs.
   */
  evaluateOutputDelta?(
    prevOutput: unknown,
    currentOutput: unknown,
    options?: DeltaEvaluationOptions,
  ): RoutineDeltaEvaluation;
}

export const DEFAULT_IGNORE_KEYS: readonly string[] = Object.freeze([
  "durationMs",
  "timestamp",
  "runId",
  "attemptId",
  "executionId",
  "messageId",
  "taskId",
  "createdAt",
  "updatedAt",
  "startedAt",
  "finishedAt",
  "nonce",
  "leaseOwner",
  "leaseFence",
]);

/**
 * 32-bit MurmurHash3 implementation in pure TypeScript.
 * Deterministic across Node, Browser, Electron, and React Native.
 */
export function murmurHash3(input: string, seed = 0): string {
  let h1 = seed >>> 0;
  const c1 = 0xcc9e2d51;
  const c2 = 0x1b873593;
  const len = input.length;

  for (let i = 0; i < len; i += 1) {
    let k1 = input.charCodeAt(i) & 0xffff;
    k1 = Math.imul(k1, c1);
    k1 = (k1 << 15) | (k1 >>> 17);
    k1 = Math.imul(k1, c2);

    h1 ^= k1;
    h1 = (h1 << 13) | (h1 >>> 19);
    h1 = (Math.imul(h1, 5) + 0xe6546b64) >>> 0;
  }

  h1 ^= len;
  h1 ^= h1 >>> 16;
  h1 = Math.imul(h1, 0x85ebca6b);
  h1 ^= h1 >>> 13;
  h1 = Math.imul(h1, 0xc2b2ae35);
  h1 ^= h1 >>> 16;

  return (h1 >>> 0).toString(16).padStart(8, "0");
}

/**
 * 64-bit MurmurHash3 composite hash returning 16-character hexadecimal string.
 * High avalanche, near-zero collision rate for structured outputs.
 */
export function murmurHash64(input: string, seed = 0): string {
  const h1 = murmurHash3(input, seed);
  const h2 = murmurHash3(input, (seed ^ 0xe99583c1) >>> 0);
  return `${h1}${h2}`;
}

/**
 * Deterministically serializes any JavaScript value into normalized JSON.
 * Recursively sorts object keys, filters volatile keys, protects against cycles,
 * and normalizes whitespace and floating point numbers.
 */
export function deterministicStringify(value: unknown, options?: NormalizationOptions): string {
  const ignoreSet = new Set(options?.ignoreKeys ?? DEFAULT_IGNORE_KEYS);
  const normalizeWs = options?.normalizeWhitespace ?? true;
  const precision = options?.numericPrecision ?? 6;
  const sortArrays = options?.sortArraysOfPrimitives ?? false;
  const ancestors = new WeakSet<object>();

  function serialize(current: unknown): string {
    if (current === null) return "null";
    if (current === undefined) return "null";

    if (typeof current === "boolean") return current ? "true" : "false";

    if (typeof current === "number") {
      if (!Number.isFinite(current)) return "null";
      if (Number.isInteger(current)) return current.toString();
      const factor = 10 ** precision;
      const rounded = Math.round(current * factor) / factor;
      return rounded.toString();
    }

    if (typeof current === "string") {
      let str = current;
      if (normalizeWs) {
        str = str.replace(/\r\n/g, "\n").trim();
      }
      return JSON.stringify(str);
    }

    if (typeof current === "bigint") {
      return JSON.stringify(`${current.toString()}n`);
    }

    if (typeof current !== "object") {
      return JSON.stringify(String(current));
    }

    if (ancestors.has(current)) {
      return '"[Circular]"';
    }

    ancestors.add(current);
    try {
      if (current instanceof Date) {
        return JSON.stringify(current.toISOString());
      }

      if (current instanceof Set) {
        const items = Array.from(current).map((item) => serialize(item));
        items.sort();
        return `[${items.join(",")}]`;
      }

      if (current instanceof Map) {
        const entries = Array.from(current.entries()).map(([k, v]) => [String(k), v]);
        entries.sort((a, b) => (a[0] as string).localeCompare(b[0] as string));
        const serializedEntries = entries.map(([k, v]) => `${JSON.stringify(k)}:${serialize(v)}`);
        return `{${serializedEntries.join(",")}}`;
      }

      if (Array.isArray(current)) {
        let items = current.map((item) => serialize(item));
        if (sortArrays && current.every((x) => typeof x === "string" || typeof x === "number")) {
          items = [...items].sort();
        }
        return `[${items.join(",")}]`;
      }

      const obj = current as Record<string, unknown>;
      const keys = Object.keys(obj)
        .filter((k) => !ignoreSet.has(k) && obj[k] !== undefined)
        .sort();

      const pairs = keys.map((k) => `${JSON.stringify(k)}:${serialize(obj[k])}`);
      return `{${pairs.join(",")}}`;
    } finally {
      ancestors.delete(current);
    }
  }

  return serialize(value);
}

/**
 * Computes deterministic content hash of any normalized value.
 */
export function computeContentHash(value: unknown, options?: NormalizationOptions): string {
  const serialized = deterministicStringify(value, options);
  return murmurHash64(serialized);
}

export interface DiffChange {
  path: string;
  kind: "added" | "removed" | "modified";
  oldValue?: unknown;
  newValue?: unknown;
}

export interface StructuralDiffResult {
  hasChanged: boolean;
  changes: DiffChange[];
  summary: string;
}

/**
 * Computes structural differences between previous and current values
 * and generates a concise, human-readable summary.
 */
export function computeStructuralDiff(
  prev: unknown,
  current: unknown,
  options?: DeltaEvaluationOptions,
): StructuralDiffResult {
  const maxSummary = options?.maxSummaryLength ?? 120;
  const changes: DiffChange[] = [];

  function diffRecursive(p: unknown, c: unknown, path: string): void {
    if (p === c) return;

    if (
      p === null ||
      c === null ||
      p === undefined ||
      c === undefined ||
      typeof p !== "object" ||
      typeof c !== "object"
    ) {
      if (typeof p === "string" && typeof c === "string") {
        const pNorm = (options?.normalizeWhitespace ?? true) ? p.replace(/\r\n/g, "\n").trim() : p;
        const cNorm = (options?.normalizeWhitespace ?? true) ? c.replace(/\r\n/g, "\n").trim() : c;
        if (pNorm !== cNorm) {
          changes.push({
            path: path || "$root",
            kind: "modified",
            oldValue: pNorm,
            newValue: cNorm,
          });
        }
        return;
      }

      changes.push({ path: path || "$root", kind: "modified", oldValue: p, newValue: c });
      return;
    }

    if (Array.isArray(p) && Array.isArray(c)) {
      if (p.length !== c.length) {
        changes.push({
          path: `${path}.length`,
          kind: "modified",
          oldValue: p.length,
          newValue: c.length,
        });
      }
      const maxLen = Math.max(p.length, c.length);
      for (let i = 0; i < maxLen; i += 1) {
        const subPath = path ? `${path}[${i}]` : `[${i}]`;
        if (i >= p.length) {
          changes.push({ path: subPath, kind: "added", newValue: c[i] });
        } else if (i >= c.length) {
          changes.push({ path: subPath, kind: "removed", oldValue: p[i] });
        } else {
          diffRecursive(p[i], c[i], subPath);
        }
      }
      return;
    }

    if (Array.isArray(p) !== Array.isArray(c)) {
      changes.push({ path: path || "$root", kind: "modified", oldValue: p, newValue: c });
      return;
    }

    const ignoreSet = new Set(options?.ignoreKeys ?? DEFAULT_IGNORE_KEYS);
    const pObj = p as Record<string, unknown>;
    const cObj = c as Record<string, unknown>;

    const pKeys = Object.keys(pObj).filter((k) => !ignoreSet.has(k));
    const cKeys = Object.keys(cObj).filter((k) => !ignoreSet.has(k));
    const allKeys = new Set([...pKeys, ...cKeys]);

    for (const key of allKeys) {
      const subPath = path ? `${path}.${key}` : key;
      const inPrev = key in pObj && pObj[key] !== undefined;
      const inCurr = key in cObj && cObj[key] !== undefined;

      if (!inPrev && inCurr) {
        changes.push({ path: subPath, kind: "added", newValue: cObj[key] });
      } else if (inPrev && !inCurr) {
        changes.push({ path: subPath, kind: "removed", oldValue: pObj[key] });
      } else {
        diffRecursive(pObj[key], cObj[key], subPath);
      }
    }
  }

  diffRecursive(prev, current, "");

  const hasChanged = changes.length > 0;
  if (!hasChanged) {
    return { hasChanged: false, changes: [], summary: "No changes" };
  }

  // Synthesize concise summary adhering to AGENTS.md microcopy constraints
  let summary = "";
  if (changes.length === 1) {
    const single = changes[0];
    if (
      single &&
      single.kind === "modified" &&
      typeof single.oldValue !== "object" &&
      typeof single.newValue !== "object"
    ) {
      summary = `${single.path}: ${String(single.oldValue)} -> ${String(single.newValue)}`;
    } else if (single?.kind === "added") {
      summary = `Added ${single.path}`;
    } else if (single?.kind === "removed") {
      summary = `Removed ${single.path}`;
    } else {
      summary = `Updated ${single?.path ?? "$root"}`;
    }
  } else if (changes.length <= 3) {
    const parts = changes.map((c) => {
      if (
        c.kind === "modified" &&
        typeof c.oldValue !== "object" &&
        typeof c.newValue !== "object"
      ) {
        return `${c.path}: ${String(c.oldValue)} -> ${String(c.newValue)}`;
      }
      return `${c.kind} ${c.path}`;
    });
    summary = parts.join("; ");
  } else {
    const added = changes.filter((c) => c.kind === "added").length;
    const removed = changes.filter((c) => c.kind === "removed").length;
    const modified = changes.filter((c) => c.kind === "modified").length;
    const parts: string[] = [];
    if (added > 0) parts.push(`${added} added`);
    if (removed > 0) parts.push(`${removed} removed`);
    if (modified > 0) parts.push(`${modified} modified`);
    const keySamples = changes
      .slice(0, 2)
      .map((c) => c.path)
      .join(", ");
    summary = `${changes.length} changes (${parts.join(", ")}; e.g. ${keySamples})`;
  }

  if (summary.length > maxSummary) {
    summary = `${summary.slice(0, maxSummary - 1)}…`;
  }

  return { hasChanged, changes, summary };
}

/**
 * Evaluates delta between two outputs.
 */
export function evaluateOutputDelta(
  prevOutput: unknown,
  currentOutput: unknown,
  options?: DeltaEvaluationOptions,
): RoutineDeltaEvaluation {
  const currentHash = computeContentHash(currentOutput, options);
  if (prevOutput === undefined || prevOutput === null) {
    return {
      hasChanged: true,
      deltaSummary: "Initial routine execution",
      changeHash: currentHash,
    };
  }

  const prevHash = computeContentHash(prevOutput, options);
  if (prevHash === currentHash) {
    return {
      hasChanged: false,
      deltaSummary: "No changes",
      changeHash: currentHash,
    };
  }

  const diff = computeStructuralDiff(prevOutput, currentOutput, options);
  return {
    hasChanged: diff.hasChanged,
    deltaSummary: diff.summary,
    changeHash: currentHash,
  };
}

/**
 * Pure function evaluating notification decision for routine run completion or failure.
 */
export function evaluateRoutineNotification(params: {
  policy: RoutineNotificationPolicy;
  prevOutput?: unknown;
  prevHash?: string;
  currentOutput?: unknown;
  status: "completed" | "failed";
  error?: string;
  routineName?: string;
  botName?: string;
  options?: DeltaEvaluationOptions;
}): RoutineNotificationDecision {
  const {
    policy,
    prevOutput,
    prevHash,
    currentOutput,
    status,
    error,
    routineName,
    botName,
    options,
  } = params;
  const currentHash = computeContentHash(currentOutput, options);
  const titleBase = routineName || botName || "Routine";

  // Mode: never
  if (policy.notifyMode === "never") {
    return {
      shouldNotify: false,
      suppressReason: "never_mode",
      hasChanged: false,
      changeHash: currentHash,
      prevHash,
      earconCue: null,
      markUnread: false,
      quiet: true,
    };
  }

  // Failure path
  if (status === "failed") {
    if (
      policy.notifyMode === "on_failure" ||
      policy.notifyMode === "on_change" ||
      policy.notifyMode === "always"
    ) {
      return {
        shouldNotify: true,
        hasChanged: true,
        changeHash: currentHash,
        prevHash,
        deltaSummary: error || "Routine failed",
        earconCue: "routine_failure",
        markUnread: true,
        quiet: false,
        notificationPayload: {
          kind: "failure",
          title: `${titleBase} failed`,
          body: error ? error.slice(0, 180) : "Routine failed",
        },
      };
    }
  }

  // Mode: on_failure (but status is completed)
  if (policy.notifyMode === "on_failure") {
    return {
      shouldNotify: false,
      suppressReason: "success_in_failure_mode",
      hasChanged: false,
      changeHash: currentHash,
      prevHash,
      earconCue: "routine_completed_quiet",
      markUnread: false,
      quiet: true,
    };
  }

  // Delta comparison for on_change and always
  let hasChanged = true;
  let deltaSummary: string | undefined;

  if (prevHash) {
    hasChanged = policy.evaluateDelta(prevHash, currentHash);
    if (hasChanged && prevOutput !== undefined) {
      const diff = computeStructuralDiff(prevOutput, currentOutput, options);
      deltaSummary = diff.summary;
    }
  } else if (prevOutput !== undefined) {
    const delta = evaluateOutputDelta(prevOutput, currentOutput, options);
    hasChanged = delta.hasChanged;
    deltaSummary = delta.deltaSummary;
  } else {
    // No previous run found - first run
    hasChanged = true;
    deltaSummary = "Initial execution";
  }

  // Mode: on_change
  if (policy.notifyMode === "on_change") {
    if (!hasChanged) {
      return {
        shouldNotify: false,
        suppressReason: "unchanged",
        hasChanged: false,
        changeHash: currentHash,
        prevHash,
        deltaSummary: "No changes",
        earconCue: "routine_completed_quiet",
        markUnread: false,
        quiet: true,
      };
    }

    const bodyText = deltaSummary || "Routine output changed";
    return {
      shouldNotify: true,
      hasChanged: true,
      changeHash: currentHash,
      prevHash,
      deltaSummary,
      earconCue: "routine_changed",
      markUnread: true,
      quiet: false,
      notificationPayload: {
        kind: "completion",
        title: `${titleBase}: change detected`,
        body: bodyText.slice(0, 180),
      },
    };
  }

  // Mode: always
  const alwaysBody =
    deltaSummary || (typeof currentOutput === "string" ? currentOutput : "Routine completed");
  return {
    shouldNotify: true,
    hasChanged,
    changeHash: currentHash,
    prevHash,
    deltaSummary,
    earconCue: hasChanged ? "routine_changed" : "routine_completed_quiet",
    markUnread: true,
    quiet: false,
    notificationPayload: {
      kind: "completion",
      title: `${titleBase} finished`,
      body: alwaysBody.slice(0, 180),
    },
  };
}

/**
 * Resolves notification policy mode with backwards compatibility for legacy boolean notify flags.
 */
export function resolveRoutineNotifyMode(
  mode?: RoutineNotifyMode | null,
  legacyNotify?: boolean,
): RoutineNotifyMode {
  if (mode) return mode;
  if (legacyNotify === false) return "never";
  return "on_change";
}

/**
 * Reference class implementation of RoutineNotificationPolicy.
 */
export class RoutinePolicy implements RoutineNotificationPolicy {
  public readonly notifyMode: RoutineNotifyMode;

  constructor(notifyMode: RoutineNotifyMode = "on_change") {
    this.notifyMode = notifyMode;
  }

  evaluateDelta(prevOutputHash: string, currentOutputHash: string): boolean {
    return prevOutputHash !== currentOutputHash;
  }

  evaluateOutputDelta(
    prevOutput: unknown,
    currentOutput: unknown,
    options?: DeltaEvaluationOptions,
  ): RoutineDeltaEvaluation {
    return evaluateOutputDelta(prevOutput, currentOutput, options);
  }
}

export { RoutinePolicy as RoutinePolicyEvaluator };