import { omit, pick } from "convex-helpers";
import { v } from "convex/values";
import {
  type StreamDelta,
  vStreamDelta,
  vStreamMessage,
} from "../validators.js";
import { api, internal } from "./_generated/api.js";
import type { Id } from "./_generated/dataModel.js";
import {
  internalMutation,
  mutation,
  type MutationCtx,
  query,
  action,
} from "./_generated/server.js";
import schema from "./schema.js";
import { stream } from "convex-helpers/server/stream";
import { mergedStream } from "convex-helpers/server/stream";
import { paginator } from "convex-helpers/server/pagination";

const SECOND = 1000;
const MINUTE = 60 * SECOND;

const MAX_DELTAS_PER_REQUEST = 1000;
const MAX_DELTAS_PER_STREAM = 100;
const TIMEOUT_INTERVAL = 10 * MINUTE;
const DELETE_STREAM_DELAY = MINUTE * 5; // 5 minutes

const deltaValidator = schema.tables.streamDeltas.validator;

export const addDelta = mutation({
  args: deltaValidator,
  returns: v.boolean(),
  handler: async (ctx, args) => {
    await ctx.db.insert("streamDeltas", args);
    await heartbeatStream(ctx, { streamId: args.streamId });
    const stream = await ctx.db.get(args.streamId);
    if (stream?.state.kind !== "streaming") {
      console.warn(`Stream is not streaming: ${args.streamId}`);
      return false;
    }
    return true;
  },
});

export const listDeltas = query({
  args: {
    threadId: v.id("threads"),
    cursors: v.array(
      v.object({
        streamId: v.id("streamingMessages"),
        cursor: v.number(),
      })
    ),
  },
  returns: v.array(vStreamDelta),
  handler: async (ctx, args): Promise<StreamDelta[]> => {
    let totalDeltas = 0;
    const deltas: StreamDelta[] = [];
    for (const cursor of args.cursors) {
      const streamDeltas = await ctx.db
        .query("streamDeltas")
        .withIndex("streamId_start_end", (q) =>
          q.eq("streamId", cursor.streamId).gte("start", cursor.cursor)
        )
        .take(
          Math.min(MAX_DELTAS_PER_STREAM, MAX_DELTAS_PER_REQUEST - totalDeltas)
        );
      totalDeltas += streamDeltas.length;
      deltas.push(
        ...streamDeltas.map((d) =>
          pick(d, ["streamId", "start", "end", "parts"])
        )
      );
      if (totalDeltas >= MAX_DELTAS_PER_REQUEST) {
        break;
      }
    }
    return deltas;
  },
});

export const create = mutation({
  args: omit(schema.tables.streamingMessages.validator.fields, ["state"]),
  returns: v.id("streamingMessages"),
  handler: async (ctx, args) => {
    const state = {
      kind: "streaming" as const,
      lastHeartbeat: Date.now(),
    };
    const streamId = await ctx.db.insert("streamingMessages", {
      ...args,
      state,
    });
    const timeoutFnId = await ctx.scheduler.runAfter(
      TIMEOUT_INTERVAL,
      internal.streams.timeoutStream,
      { streamId }
    );
    await ctx.db.patch(streamId, { state: { ...state, timeoutFnId } });
    return streamId;
  },
});

export const list = query({
  args: {
    threadId: v.id("threads"),
  },
  returns: v.array(vStreamMessage),
  handler: async (ctx, args) => {
    return ctx.db
      .query("streamingMessages")
      .withIndex("threadId_state_order_stepOrder", (q) =>
        q.eq("threadId", args.threadId).eq("state.kind", "streaming")
      )
      .order("desc")
      .take(100)
      .then((msgs) =>
        msgs.map((m) => ({
          streamId: m._id,
          ...pick(m, [
            "order",
            "stepOrder",
            "userId",
            "agentName",
            "model",
            "provider",
            "providerOptions",
          ]),
        }))
      );
  },
});

export const finish = mutation({
  args: {
    streamId: v.id("streamingMessages"),
    finalDelta: v.optional(deltaValidator),
  },
  returns: v.null(),
  handler: async (ctx, args) => {
    if (args.finalDelta) {
      await ctx.db.insert("streamDeltas", args.finalDelta);
    }
    const stream = await ctx.db.get(args.streamId);
    if (!stream) {
      throw new Error(`Stream not found: ${args.streamId}`);
    }
    if (stream.state.kind !== "streaming") {
      console.warn(
        `Stream trying to finish but not currently streaming: ${args.streamId}`
      );
      return;
    }
    if (stream.state.timeoutFnId) {
      const timeoutFn = await ctx.db.system.get(stream.state.timeoutFnId);
      if (timeoutFn?.state.kind === "pending") {
        await ctx.scheduler.cancel(stream.state.timeoutFnId);
      }
    }
    await ctx.db.patch(args.streamId, {
      state: { kind: "finished", endedAt: Date.now() },
    });
    await ctx.scheduler.runAfter(
      DELETE_STREAM_DELAY,
      api.streams.deleteStreamAsync,
      { streamId: args.streamId }
    );
  },
});

async function heartbeatStream(
  ctx: MutationCtx,
  args: { streamId: Id<"streamingMessages"> }
) {
  const stream = await ctx.db.get(args.streamId);
  if (!stream) {
    console.warn("Stream not found", args.streamId);
    return;
  }
  if (stream.state.kind !== "streaming") {
    console.warn("Stream is not streaming", args.streamId);
    return;
  }
  if (Date.now() - stream.state.lastHeartbeat < TIMEOUT_INTERVAL / 4) {
    // Debounce heartbeating.
    return;
  }
  if (!stream.state.timeoutFnId) {
    throw new Error("Stream has no timeout function");
  }
  const timeoutFn = await ctx.db.system.get(stream.state.timeoutFnId);
  if (!timeoutFn) {
    throw new Error("Timeout function not found");
  }
  if (timeoutFn.state.kind !== "pending") {
    throw new Error("Timeout function is not pending");
  }
  await ctx.scheduler.cancel(stream.state.timeoutFnId);
  const timeoutFnId = await ctx.scheduler.runAfter(
    TIMEOUT_INTERVAL,
    internal.streams.timeoutStream,
    { streamId: args.streamId }
  );
  await ctx.db.patch(args.streamId, {
    state: {
      kind: "streaming",
      lastHeartbeat: Date.now(),
      timeoutFnId,
    },
  });
}

export const timeoutStream = internalMutation({
  args: { streamId: v.id("streamingMessages") },
  returns: v.null(),
  handler: async (ctx, args) => {
    const stream = await ctx.db.get(args.streamId);
    if (!stream) {
      console.warn("Stream not found", args.streamId);
      return;
    }
    await ctx.db.patch(args.streamId, {
      state: {
        kind: "finished",
        endedAt: Date.now(),
      },
    });
  },
});

async function deletePageForStreamId(
  ctx: MutationCtx,
  args: { streamId: Id<"streamingMessages">; cursor?: string }
) {
  const deltas = await paginator(ctx.db, schema)
    .query("streamDeltas")
    .withIndex("streamId_start_end", (q) => q.eq("streamId", args.streamId))
    .paginate({
      numItems: MAX_DELTAS_PER_REQUEST,
      cursor: args.cursor ?? null,
    });
  await Promise.all(deltas.page.map((d) => ctx.db.delete(d._id)));
  if (deltas.isDone) {
    await ctx.db.delete(args.streamId);
  }
  return deltas;
}

export async function deleteStreamsPageForThreadId(
  ctx: MutationCtx,
  args: { threadId: Id<"threads">; streamOrder?: number; deltaCursor?: string }
) {
  const allStreamMessages =
    schema.tables.streamingMessages.validator.fields.state.members
      .flatMap((state) => state.fields.kind.value)
      .map((stateKind) =>
        stream(ctx.db, schema)
          .query("streamingMessages")
          .withIndex("threadId_state_order_stepOrder", (q) =>
            q
              .eq("threadId", args.threadId)
              .eq("state.kind", stateKind)
              .gte("order", args.streamOrder ?? 0)
          )
      );
  let deltaCursor = args.deltaCursor;
  const streamMessage = await mergedStream(allStreamMessages, [
    "threadId",
    "state.kind",
    "order",
    "stepOrder",
  ]).first();
  if (!streamMessage) {
    return {
      isDone: true,
      streamOrder: undefined,
      deltaCursor: undefined,
    };
  }
  const result = await deletePageForStreamId(ctx, {
    streamId: streamMessage._id,
    cursor: deltaCursor,
  });
  if (result.isDone) {
    deltaCursor = undefined;
  }
  return {
    isDone: false,
    streamOrder: streamMessage.order,
    deltaCursor,
  };
}

export const deleteStreamsPageForThreadIdMutation = internalMutation({
  args: {
    threadId: v.id("threads"),
    streamOrder: v.optional(v.number()),
    deltaCursor: v.optional(v.string()),
  },
  returns: v.object({
    isDone: v.boolean(),
    streamOrder: v.optional(v.number()),
    deltaCursor: v.optional(v.string()),
  }),
  handler: deleteStreamsPageForThreadId,
});

export const deleteAllStreamsForThreadIdAsync = mutation({
  args: {
    threadId: v.id("threads"),
    streamOrder: v.optional(v.number()),
    deltaCursor: v.optional(v.string()),
  },
  returns: v.object({
    isDone: v.boolean(),
    streamOrder: v.optional(v.number()),
    deltaCursor: v.optional(v.string()),
  }),
  handler: async (ctx, args) => {
    const result = await deleteStreamsPageForThreadId(ctx, args);
    if (!result.isDone) {
      await ctx.scheduler.runAfter(
        0,
        api.streams.deleteAllStreamsForThreadIdAsync,
        {
          threadId: args.threadId,
          streamOrder: result.streamOrder,
          deltaCursor: result.deltaCursor,
        }
      );
    } else {
      await ctx.db.delete(args.threadId);
    }
    return result;
  },
});

export const deleteStreamSync = mutation({
  args: { streamId: v.id("streamingMessages") },
  returns: v.null(),
  handler: async (ctx, args) => {
    let deltas = await deletePageForStreamId(ctx, args);
    while (!deltas.isDone) {
      deltas = await deletePageForStreamId(ctx, {
        ...args,
        cursor: deltas.continueCursor,
      });
    }
  },
});

export const deleteStreamAsync = mutation({
  args: { streamId: v.id("streamingMessages"), cursor: v.optional(v.string()) },
  returns: v.null(),
  handler: async (ctx, args) => {
    const result = await deletePageForStreamId(ctx, args);
    if (!result.isDone) {
      await ctx.scheduler.runAfter(0, api.streams.deleteStreamAsync, {
        streamId: args.streamId,
        cursor: result.continueCursor,
      });
    }
  },
});

export const deleteAllStreamsForThreadIdSync = action({
  args: { threadId: v.id("threads") },
  returns: v.null(),
  handler: async (ctx, args) => {
    let result = await ctx.runMutation(
      internal.streams.deleteStreamsPageForThreadIdMutation,
      args
    );
    while (!result.isDone) {
      result = await ctx.runMutation(
        internal.streams.deleteStreamsPageForThreadIdMutation,
        {
          ...args,
          streamOrder: result.streamOrder,
          deltaCursor: result.deltaCursor,
        }
      );
    }
  },
});