import { getChannelPlugin, normalizeChannelId } from "../../channels/plugins/index.js";
import type { BlockStreamingCoalesceConfig } from "../../config/types.js";
import type { OpenClawConfig } from "../../config/types.openclaw.js";
import { resolveChannelStreamingBlockCoalesce } from "../../plugin-sdk/channel-streaming.js";
import { resolveAccountEntry } from "../../routing/account-lookup.js";
import { normalizeAccountId } from "../../routing/session-key.js";
import { normalizeMessageChannel } from "../../utils/message-channel.js";
import { resolveChunkMode, resolveTextChunkLimit, type TextChunkProvider } from "../chunk.js";

const DEFAULT_BLOCK_STREAM_MIN = 800;
const DEFAULT_BLOCK_STREAM_MAX = 1200;
const DEFAULT_BLOCK_STREAM_COALESCE_IDLE_MS = 1000;

function resolveProviderChunkContext(
  cfg: OpenClawConfig | undefined,
  provider?: string,
  accountId?: string | null,
) {
  const providerKey = provider
    ? (normalizeMessageChannel(provider) as TextChunkProvider | undefined)
    : undefined;
  const providerId = providerKey ? normalizeChannelId(providerKey) : null;
  const providerChunkLimit = providerId
    ? getChannelPlugin(providerId)?.outbound?.textChunkLimit
    : undefined;
  const textLimit = resolveTextChunkLimit(cfg, providerKey, accountId, {
    fallbackLimit: providerChunkLimit,
  });
  return { providerKey, providerId, textLimit };
}

type ProviderBlockStreamingConfig = {
  blockStreamingCoalesce?: BlockStreamingCoalesceConfig;
  streaming?: unknown;
  accounts?: Record<
    string,
    { blockStreamingCoalesce?: BlockStreamingCoalesceConfig; streaming?: unknown }
  >;
};

function resolveProviderBlockStreamingCoalesce(params: {
  cfg: OpenClawConfig | undefined;
  providerKey?: TextChunkProvider;
  accountId?: string | null;
}): BlockStreamingCoalesceConfig | undefined {
  const { cfg, providerKey, accountId } = params;
  if (!cfg || !providerKey) {
    return undefined;
  }
  const providerCfg = (cfg as Record<string, unknown>)[providerKey];
  if (!providerCfg || typeof providerCfg !== "object") {
    return undefined;
  }
  const normalizedAccountId = normalizeAccountId(accountId);
  const typed = providerCfg as ProviderBlockStreamingConfig;
  const accountCfg = resolveAccountEntry(typed.accounts, normalizedAccountId);
  return (
    resolveChannelStreamingBlockCoalesce(accountCfg) ??
    resolveChannelStreamingBlockCoalesce(typed) ??
    accountCfg?.blockStreamingCoalesce ??
    typed.blockStreamingCoalesce
  );
}

export type BlockStreamingCoalescing = {
  minChars: number;
  maxChars: number;
  idleMs: number;
  joiner: string;
  /** Internal escape hatch for transports that truly need per-enqueue flushing. */
  flushOnEnqueue?: boolean;
};

export type BlockStreamingChunking = {
  minChars: number;
  maxChars: number;
  breakPreference: "paragraph" | "newline" | "sentence";
  flushOnParagraph?: boolean;
};

export function clampPositiveInteger(
  value: unknown,
  fallback: number,
  bounds: { min: number; max: number },
): number {
  if (typeof value !== "number" || !Number.isFinite(value)) {
    return fallback;
  }
  const rounded = Math.round(value);
  if (rounded < bounds.min) {
    return bounds.min;
  }
  if (rounded > bounds.max) {
    return bounds.max;
  }
  return rounded;
}

export function resolveEffectiveBlockStreamingConfig(params: {
  cfg: OpenClawConfig | undefined;
  provider?: string;
  accountId?: string | null;
  chunking?: BlockStreamingChunking;
  /** Optional upper bound for chunking/coalescing max chars. */
  maxChunkChars?: number;
  /** Optional coalescer idle flush override in milliseconds. */
  coalesceIdleMs?: number;
}): {
  chunking: BlockStreamingChunking;
  coalescing: BlockStreamingCoalescing;
} {
  const { textLimit } = resolveProviderChunkContext(params.cfg, params.provider, params.accountId);
  const chunkingDefaults =
    params.chunking ?? resolveBlockStreamingChunking(params.cfg, params.provider, params.accountId);
  const chunkingMax = clampPositiveInteger(params.maxChunkChars, chunkingDefaults.maxChars, {
    min: 1,
    max: Math.max(1, textLimit),
  });
  const chunking: BlockStreamingChunking = {
    ...chunkingDefaults,
    minChars: Math.min(chunkingDefaults.minChars, chunkingMax),
    maxChars: chunkingMax,
  };
  const coalescingDefaults = resolveBlockStreamingCoalescing(
    params.cfg,
    params.provider,
    params.accountId,
    chunking,
  );
  const coalescingMax = Math.max(
    1,
    Math.min(coalescingDefaults?.maxChars ?? chunking.maxChars, chunking.maxChars),
  );
  const coalescingMin = Math.min(coalescingDefaults?.minChars ?? chunking.minChars, coalescingMax);
  const coalescingIdleMs = clampPositiveInteger(
    params.coalesceIdleMs,
    coalescingDefaults?.idleMs ?? DEFAULT_BLOCK_STREAM_COALESCE_IDLE_MS,
    { min: 0, max: 5_000 },
  );
  const coalescing: BlockStreamingCoalescing = {
    minChars: coalescingMin,
    maxChars: coalescingMax,
    idleMs: coalescingIdleMs,
    joiner:
      coalescingDefaults?.joiner ??
      (chunking.breakPreference === "sentence"
        ? " "
        : chunking.breakPreference === "newline"
          ? "\n"
          : "\n\n"),
    ...(coalescingDefaults?.flushOnEnqueue === true ? { flushOnEnqueue: true } : {}),
  };

  return { chunking, coalescing };
}

export function resolveBlockStreamingChunking(
  cfg: OpenClawConfig | undefined,
  provider?: string,
  accountId?: string | null,
): BlockStreamingChunking {
  const { providerKey, textLimit } = resolveProviderChunkContext(cfg, provider, accountId);
  const chunkCfg = cfg?.agents?.defaults?.blockStreamingChunk;

  // When chunkMode="newline", outbound delivery prefers paragraph boundaries.
  // Keep the chunker paragraph-aware during streaming, but still let minChars
  // control when a buffered paragraph is ready to flush.
  const chunkMode = resolveChunkMode(cfg, providerKey, accountId);

  const maxRequested = Math.max(1, Math.floor(chunkCfg?.maxChars ?? DEFAULT_BLOCK_STREAM_MAX));
  const maxChars = Math.max(1, Math.min(maxRequested, textLimit));
  const minFallback = DEFAULT_BLOCK_STREAM_MIN;
  const minRequested = Math.max(1, Math.floor(chunkCfg?.minChars ?? minFallback));
  const minChars = Math.min(minRequested, maxChars);
  const breakPreference =
    chunkCfg?.breakPreference === "newline" || chunkCfg?.breakPreference === "sentence"
      ? chunkCfg.breakPreference
      : "paragraph";
  return {
    minChars,
    maxChars,
    breakPreference,
    flushOnParagraph: chunkMode === "newline",
  };
}

export function resolveBlockStreamingCoalescing(
  cfg: OpenClawConfig | undefined,
  provider?: string,
  accountId?: string | null,
  chunking?: {
    minChars: number;
    maxChars: number;
    breakPreference: "paragraph" | "newline" | "sentence";
  },
): BlockStreamingCoalescing | undefined {
  const { providerKey, providerId, textLimit } = resolveProviderChunkContext(
    cfg,
    provider,
    accountId,
  );

  const providerDefaults = providerId
    ? getChannelPlugin(providerId)?.streaming?.blockStreamingCoalesceDefaults
    : undefined;
  const providerCfg = resolveProviderBlockStreamingCoalesce({
    cfg,
    providerKey,
    accountId,
  });
  const coalesceCfg = providerCfg ?? cfg?.agents?.defaults?.blockStreamingCoalesce;
  const minRequested = Math.max(
    1,
    Math.floor(
      coalesceCfg?.minChars ??
        providerDefaults?.minChars ??
        chunking?.minChars ??
        DEFAULT_BLOCK_STREAM_MIN,
    ),
  );
  const maxRequested = Math.max(1, Math.floor(coalesceCfg?.maxChars ?? textLimit));
  const maxChars = Math.max(1, Math.min(maxRequested, textLimit));
  const minChars = Math.min(minRequested, maxChars);
  const idleMs = Math.max(
    0,
    Math.floor(
      coalesceCfg?.idleMs ?? providerDefaults?.idleMs ?? DEFAULT_BLOCK_STREAM_COALESCE_IDLE_MS,
    ),
  );
  const preference = chunking?.breakPreference ?? "paragraph";
  const joiner = preference === "sentence" ? " " : preference === "newline" ? "\n" : "\n\n";
  return {
    minChars,
    maxChars,
    idleMs,
    joiner,
  };
}