import type {
  IOPacket,
  RunMetadataChangeOperation,
  UpdateMetadataRequestBody,
} from "@trigger.dev/core/v3";
import { applyMetadataOperations, parsePacket } from "@trigger.dev/core/v3";
import type { PrismaClientOrTransaction } from "~/db.server";
import type { AuthenticatedEnvironment } from "~/services/apiAuth.server";
import { handleMetadataPacket, MetadataTooLargeError } from "~/utils/packets";
import { ServiceValidationError } from "~/v3/services/common.server";
import { Effect, Schedule, Duration, Fiber } from "effect";
import { type RuntimeFiber } from "effect/Fiber";
import { setTimeout } from "timers/promises";
import type { LogLevel } from "@trigger.dev/core/logger";
import { Logger } from "@trigger.dev/core/logger";
import type { RunStore } from "@internal/run-store";

const RUN_UPDATABLE_WINDOW_MS = 60 * 60 * 1000; // 1 hour

type BufferedRunMetadataChangeOperation = {
  runId: string;
  timestamp: number;
  operation: RunMetadataChangeOperation;
};

export type UpdateMetadataServiceOptions = {
  prisma: PrismaClientOrTransaction;
  runStore: RunStore;
  flushIntervalMs?: number;
  flushEnabled?: boolean;
  flushLoggingEnabled?: boolean;
  maximumSize?: number;
  logger?: Logger;
  logLevel?: LogLevel;
  /** Called after the batched flusher writes a run's buffered operations, with everything
   * a realtime change record needs — buffered (parent/root) updates otherwise never wake
   * live feeds. */
  onRunFlushed?: (run: {
    runId: string;
    environmentId: string;
    tags: string[];
    batchId: string | null;
    updatedAtMs: number;
  }) => void;
  // Testing hooks
  onBeforeUpdate?: (runId: string) => Promise<void>;
  onAfterRead?: (runId: string, metadataVersion: number) => Promise<void>;
};

export class UpdateMetadataService {
  private _bufferedOperations: Map<string, BufferedRunMetadataChangeOperation[]> = new Map();
  private _flushFiber: RuntimeFiber<void> | null = null;
  private readonly _prisma: PrismaClientOrTransaction;
  private readonly _runStore: RunStore;
  private readonly flushIntervalMs: number;
  private readonly flushEnabled: boolean;
  private readonly flushLoggingEnabled: boolean;
  private readonly maximumSize: number;
  private readonly logger: Logger;

  constructor(private readonly options: UpdateMetadataServiceOptions) {
    this._prisma = options.prisma;
    this._runStore = options.runStore;
    this.flushIntervalMs = options.flushIntervalMs ?? 5000;
    this.flushEnabled = options.flushEnabled ?? true;
    this.flushLoggingEnabled = options.flushLoggingEnabled ?? true;
    this.maximumSize = options.maximumSize ?? 1024 * 1024 * 1; // 1MB
    this.logger = options.logger ?? new Logger("UpdateMetadataService", options.logLevel ?? "info");

    this._startFlushing();
  }

  // Start a loop that periodically flushes buffered operations
  private _startFlushing() {
    if (!this.flushEnabled) {
      this.logger.info("[UpdateMetadataService] 🚽 Flushing disabled");

      return;
    }

    this.logger.info("[UpdateMetadataService] 🚽 Flushing started");

    // Create a program that sleeps, then processes buffered ops
    const program = Effect.gen(this, function* (_) {
      while (true) {
        // Wait for flushIntervalMs before flushing again
        yield* _(Effect.sleep(Duration.millis(this.flushIntervalMs)));

        // Atomically get and clear current operations
        const currentOperations = new Map(this._bufferedOperations);
        this._bufferedOperations.clear();

        yield* Effect.sync(() => {
          if (this.flushLoggingEnabled) {
            this.logger.debug(`[UpdateMetadataService] Flushing operations`, {
              operations: Object.fromEntries(currentOperations),
            });
          }
        });

        // If we have operations, process them
        if (currentOperations.size > 0) {
          yield* _(this._processBufferedOperations(currentOperations));
        }
      }
    }).pipe(
      // Handle any unexpected errors, ensuring program does not fail
      Effect.catchAll((error) =>
        Effect.sync(() => {
          this.logger.error("Error in flushing program:", { error });
        })
      )
    );

    // Fork the program so it runs in the background
    this._flushFiber = Effect.runFork(program as Effect.Effect<void, never, never>);
  }

  stopFlushing() {
    if (this._flushFiber) {
      Effect.runFork(Fiber.interrupt(this._flushFiber));
    }
  }

  private _processBufferedOperations = (
    operations: Map<string, BufferedRunMetadataChangeOperation[]>
  ) => {
    return Effect.gen(this, function* (_) {
      for (const [runId, ops] of operations) {
        // Process and cull operations
        const processedOps = this._cullOperations(ops);

        // If there are no operations to process, skip
        if (processedOps.length === 0) {
          continue;
        }

        yield* Effect.sync(() => {
          if (this.flushLoggingEnabled) {
            this.logger.debug(`[UpdateMetadataService] Processing operations for run`, {
              runId,
              operationsCount: processedOps.length,
            });
          }
        });

        // Update run with retry
        yield* _(
          this._updateRunWithOperations(runId, processedOps).pipe(
            // Catch MetadataTooLargeError before retry logic
            Effect.catchIf(
              (error) => error instanceof MetadataTooLargeError,
              (error) =>
                Effect.sync(() => {
                  // Log the error but don't return operations to buffer
                  console.error(
                    `[UpdateMetadataService] Dropping operations for run ${runId} due to metadata size limit:`,
                    error.message
                  );
                  if (this.flushLoggingEnabled) {
                    this.logger.warn(`[UpdateMetadataService] Metadata too large for run`, {
                      runId,
                      operationsCount: processedOps.length,
                      error: error.message,
                    });
                  }
                })
            ),
            Effect.retry(Schedule.exponential(Duration.millis(100), 1.4)),
            Effect.catchAll((error) =>
              Effect.sync(() => {
                // On complete failure, return ops to buffer
                const existingOps = this._bufferedOperations.get(runId) ?? [];
                this._bufferedOperations.set(runId, [...existingOps, ...ops]);
                console.error(`Failed to process run ${runId}:`, error);
              })
            )
          )
        );
      }
    });
  };

  private _updateRunWithOperations = (
    runId: string,
    operations: BufferedRunMetadataChangeOperation[]
  ) => {
    return Effect.gen(this, function* (_) {
      // Fetch current run (+ the realtime membership keys, so a flush can publish)
      const run = yield* _(
        Effect.tryPromise(() =>
          this._runStore.findRun(
            { id: runId },
            {
              select: {
                id: true,
                metadata: true,
                metadataType: true,
                metadataVersion: true,
                runtimeEnvironmentId: true,
                runTags: true,
                batchId: true,
              },
            },
            this._prisma
          )
        )
      );

      if (!run) {
        return yield* _(Effect.fail(new Error(`Run ${runId} not found`)));
      }

      // Testing hook after read
      if (this.options.onAfterRead) {
        yield* _(Effect.tryPromise(() => this.options.onAfterRead!(runId, run.metadataVersion)));
      }

      const metadata = yield* _(
        Effect.tryPromise(() =>
          run.metadata
            ? parsePacket({ data: run.metadata, dataType: run.metadataType })
            : Promise.resolve({})
        )
      );

      // Apply operations and update
      const applyResult = applyMetadataOperations(
        metadata,
        operations.map((op) => op.operation)
      );

      if (applyResult.unappliedOperations.length === operations.length) {
        this.logger.warn(`No operations applied for run ${runId}`);
        // If no operations were applied, return
        return;
      }

      // Stringify the metadata
      const newMetadataPacket = yield* _(
        Effect.try(() =>
          handleMetadataPacket(applyResult.newMetadata, run.metadataType, this.maximumSize)
        ).pipe(
          Effect.mapError((error) => {
            // Preserve the original error if it's MetadataTooLargeError
            if ("cause" in error && error.cause instanceof MetadataTooLargeError) {
              return error.cause;
            }
            return error;
          })
        )
      );

      if (!newMetadataPacket) {
        // Log and skip if metadata is invalid
        this.logger.warn(`Invalid metadata after operations, skipping update`);
        return;
      }

      // Testing hook before update
      if (this.options.onBeforeUpdate) {
        yield* _(Effect.tryPromise(() => this.options.onBeforeUpdate!(runId)));
      }

      // Stamp updatedAt explicitly so the realtime publish can carry the exact committed
      // value without a follow-up read (updateMany can't RETURNING).
      const writeTime = new Date();
      const result = yield* _(
        Effect.tryPromise(() =>
          this._runStore.updateMetadata(
            runId,
            {
              metadata: newMetadataPacket.data!,
              metadataVersion: { increment: 1 },
              updatedAt: writeTime,
            },
            { expectedMetadataVersion: run.metadataVersion },
            this._prisma
          )
        )
      );

      if (result.count === 0) {
        yield* Effect.sync(() => {
          this.logger.warn(`Optimistic lock failed for run ${runId}`, {
            metadataVersion: run.metadataVersion,
          });
        });

        return yield* _(Effect.fail(new Error("Optimistic lock failed")));
      }

      yield* Effect.sync(() => {
        this.options.onRunFlushed?.({
          runId,
          environmentId: run.runtimeEnvironmentId,
          tags: run.runTags,
          batchId: run.batchId,
          updatedAtMs: writeTime.getTime(),
        });
      });

      return result;
    });
  };

  private _cullOperations(
    operations: BufferedRunMetadataChangeOperation[]
  ): BufferedRunMetadataChangeOperation[] {
    // Sort by timestamp
    const sortedOps = [...operations].sort((a, b) => a.timestamp - b.timestamp);

    // Track latest set operations by key
    const latestSetOps = new Map<string, BufferedRunMetadataChangeOperation>();
    const resultOps: BufferedRunMetadataChangeOperation[] = [];

    for (const op of sortedOps) {
      if (op.operation.type === "set") {
        latestSetOps.set(op.operation.key, op);
      } else {
        resultOps.push(op);
      }
    }

    // Add winning set operations
    resultOps.push(...latestSetOps.values());

    return resultOps;
  }

  public async call(
    runId: string,
    body: UpdateMetadataRequestBody,
    environment?: AuthenticatedEnvironment
  ) {
    const runIdType = runId.startsWith("run_") ? "friendly" : "internal";

    const taskRun = await this._runStore.findRun(
      environment
        ? {
            runtimeEnvironmentId: environment.id,
            ...(runIdType === "internal" ? { id: runId } : { friendlyId: runId }),
          }
        : {
            ...(runIdType === "internal" ? { id: runId } : { friendlyId: runId }),
          },
      {
        select: {
          id: true,
          batchId: true,
          runTags: true,
          completedAt: true,
          status: true,
          metadata: true,
          metadataType: true,
          metadataVersion: true,
          parentTaskRun: {
            select: {
              id: true,
              status: true,
            },
          },
          rootTaskRun: {
            select: {
              id: true,
              status: true,
            },
          },
        },
      },
      this._prisma
    );

    if (!taskRun) {
      return;
    }

    if (!this.#isRunUpdatable(taskRun)) {
      throw new ServiceValidationError("Cannot update metadata for a completed run");
    }

    if (body.parentOperations && body.parentOperations.length > 0) {
      this.#ingestRunOperations(taskRun.parentTaskRun?.id ?? taskRun.id, body.parentOperations);
    }

    if (body.rootOperations && body.rootOperations.length > 0) {
      this.#ingestRunOperations(taskRun.rootTaskRun?.id ?? taskRun.id, body.rootOperations);
    }

    const result = await this.#updateRunMetadata({
      runId: taskRun.id,
      body,
      existingMetadata: {
        data: taskRun.metadata ?? undefined,
        dataType: taskRun.metadataType,
      },
    });

    return {
      metadata: result?.metadata,
      // Internal id + membership keys, so callers can publish full realtime records the router routes by index.
      runId: taskRun.id,
      batchId: taskRun.batchId,
      runTags: taskRun.runTags,
      // The committed row's updatedAt — the realtime watermark. Undefined when nothing was
      // written here (no-op, or buffered for the flusher, which publishes itself).
      updatedAtMs: result?.updatedAtMs,
    };
  }

  async #updateRunMetadata({
    runId,
    body,
    existingMetadata,
  }: {
    runId: string;
    body: UpdateMetadataRequestBody;
    existingMetadata: IOPacket;
  }): Promise<{ metadata: Record<string, unknown> | undefined; updatedAtMs?: number }> {
    if (Array.isArray(body.operations)) {
      return this.#updateRunMetadataWithOperations(runId, body.operations);
    } else {
      return this.#updateRunMetadataDirectly(runId, body, existingMetadata);
    }
  }

  async #updateRunMetadataWithOperations(
    runId: string,
    operations: RunMetadataChangeOperation[]
  ): Promise<{ metadata: Record<string, unknown> | undefined; updatedAtMs?: number }> {
    const MAX_RETRIES = 3;
    let attempts = 0;

    while (attempts <= MAX_RETRIES) {
      // Fetch the latest run data
      const run = await this._runStore.findRun(
        { id: runId },
        {
          select: { metadata: true, metadataType: true, metadataVersion: true },
        },
        this._prisma
      );

      if (!run) {
        throw new Error(`Run ${runId} not found`);
      }

      // Testing hook after read
      if (this.options.onAfterRead) {
        await this.options.onAfterRead(runId, run.metadataVersion);
      }

      // Parse the current metadata
      const currentMetadata = await (run.metadata
        ? parsePacket({ data: run.metadata, dataType: run.metadataType })
        : Promise.resolve({}));

      // Apply operations to the current metadata
      const applyResults = applyMetadataOperations(currentMetadata, operations);

      // If no operations were applied, return the current metadata (nothing written)
      if (applyResults.unappliedOperations.length === operations.length) {
        return { metadata: currentMetadata };
      }

      const newMetadataPacket = handleMetadataPacket(
        applyResults.newMetadata,
        run.metadataType,
        this.maximumSize
      );

      if (!newMetadataPacket) {
        throw new ServiceValidationError("Unable to update metadata");
      }

      // Testing hook before update
      if (this.options.onBeforeUpdate) {
        await this.options.onBeforeUpdate(runId);
      }

      // Update with optimistic locking; updatedAt stamped explicitly so the caller can
      // publish the exact committed watermark without a follow-up read.
      const writeTime = new Date();
      const result = await this._runStore.updateMetadata(
        runId,
        {
          metadata: newMetadataPacket.data!,
          metadataType: newMetadataPacket.dataType,
          metadataVersion: {
            increment: 1,
          },
          updatedAt: writeTime,
        },
        { expectedMetadataVersion: run.metadataVersion },
        this._prisma
      );

      if (result.count === 0) {
        if (this.flushLoggingEnabled) {
          this.logger.debug(
            `[updateRunMetadataWithOperations] Optimistic lock failed for run ${runId}`,
            {
              metadataVersion: run.metadataVersion,
            }
          );
        }

        // If this was our last attempt, buffer the operations and return optimistically
        // (no watermark — the flusher writes later and publishes itself).
        if (attempts === MAX_RETRIES) {
          this.#ingestRunOperations(runId, operations);
          return { metadata: applyResults.newMetadata };
        }

        // Otherwise sleep and try again
        await setTimeout(100 * Math.pow(1.4, attempts));
        attempts++;
        continue;
      }

      if (this.flushLoggingEnabled) {
        this.logger.debug(`[updateRunMetadataWithOperations] Updated metadata for run`, {
          metadata: applyResults.newMetadata,
          operations: operations,
          runId,
        });
      }

      // Success! Return the new metadata
      return { metadata: applyResults.newMetadata, updatedAtMs: writeTime.getTime() };
    }

    return { metadata: undefined };
  }

  // Checks to see if a run is updatable
  // if there is no completedAt, the run is updatable
  // if the run is completed, but the completedAt is within the last 10 minutes, the run is updatable
  #isRunUpdatable(run: { completedAt: Date | null }) {
    if (!run.completedAt) {
      return true;
    }

    return run.completedAt.getTime() > Date.now() - RUN_UPDATABLE_WINDOW_MS;
  }

  async #updateRunMetadataDirectly(
    runId: string,
    body: UpdateMetadataRequestBody,
    existingMetadata: IOPacket
  ): Promise<{ metadata: Record<string, unknown> | undefined; updatedAtMs?: number }> {
    const metadataPacket = handleMetadataPacket(
      body.metadata,
      "application/json",
      this.maximumSize
    );

    if (!metadataPacket) {
      return { metadata: {} };
    }

    let updatedAtMs: number | undefined;

    if (
      metadataPacket.data !== "{}" ||
      (existingMetadata.data && metadataPacket.data !== existingMetadata.data)
    ) {
      if (this.flushLoggingEnabled) {
        this.logger.debug(`[updateRunMetadataDirectly] Updating metadata directly for run`, {
          metadata: metadataPacket.data,
          runId,
        });
      }

      // Update the metadata without version check; updatedAt stamped explicitly so the
      // caller can publish the exact committed watermark.
      const writeTime = new Date();
      await this._runStore.updateMetadata(
        runId,
        {
          metadata: metadataPacket?.data!,
          metadataType: metadataPacket?.dataType,
          metadataVersion: {
            increment: 1,
          },
          updatedAt: writeTime,
        },
        {},
        this._prisma
      );
      updatedAtMs = writeTime.getTime();
    }

    const newMetadata = await parsePacket(metadataPacket);
    return { metadata: newMetadata, updatedAtMs };
  }

  #ingestRunOperations(runId: string, operations: RunMetadataChangeOperation[]) {
    const bufferedOperations: BufferedRunMetadataChangeOperation[] = operations.map((operation) => {
      return {
        runId,
        timestamp: Date.now(),
        operation,
      };
    });

    if (this.flushLoggingEnabled) {
      this.logger.debug(`[ingestRunOperations] Ingesting operations for run`, {
        runId,
        bufferedOperations,
      });
    }

    const existingBufferedOperations = this._bufferedOperations.get(runId) ?? [];

    this._bufferedOperations.set(runId, [...existingBufferedOperations, ...bufferedOperations]);
  }

  // Testing method to manually trigger flush
  async flushOperations() {
    const currentOperations = new Map(this._bufferedOperations);
    this._bufferedOperations.clear();

    if (currentOperations.size > 0) {
      await Effect.runPromise(this._processBufferedOperations(currentOperations));
    }
  }
}