import type { StreamFn } from "@earendil-works/pi-agent-core";
import { streamSimple } from "@earendil-works/pi-ai";
import { streamWithPayloadPatch } from "../agents/pi-embedded-runner/stream-payload-utils.js";
import { normalizeLowercaseStringOrEmpty } from "../shared/string-coerce.js";
import type { ProviderWrapStreamFnContext } from "./plugin-entry.js";

export type ProviderStreamWrapperFactory =
  | ((streamFn: StreamFn | undefined) => StreamFn | undefined)
  | null
  | undefined
  | false;

export function composeProviderStreamWrappers(
  baseStreamFn: StreamFn | undefined,
  ...wrappers: ProviderStreamWrapperFactory[]
): StreamFn | undefined {
  return wrappers.reduce(
    (streamFn, wrapper) => (wrapper ? wrapper(streamFn) : streamFn),
    baseStreamFn,
  );
}

/** @deprecated Bundled provider stream helper; do not use from third-party plugins. */
export function defaultToolStreamExtraParams(
  extraParams?: Record<string, unknown>,
): Record<string, unknown> {
  if (extraParams?.tool_stream !== undefined) {
    return extraParams;
  }
  return {
    ...extraParams,
    tool_stream: true,
  };
}

export function createPayloadPatchStreamWrapper(
  baseStreamFn: StreamFn | undefined,
  patchPayload: (params: {
    payload: Record<string, unknown>;
    model: Parameters<StreamFn>[0];
    context: Parameters<StreamFn>[1];
    options: Parameters<StreamFn>[2];
  }) => void,
  wrapperOptions?: {
    shouldPatch?: (params: {
      model: Parameters<StreamFn>[0];
      context: Parameters<StreamFn>[1];
      options: Parameters<StreamFn>[2];
    }) => boolean;
  },
): StreamFn {
  const underlying = baseStreamFn ?? streamSimple;
  return (model, context, options) => {
    if (wrapperOptions?.shouldPatch && !wrapperOptions.shouldPatch({ model, context, options })) {
      return underlying(model, context, options);
    }
    return streamWithPayloadPatch(underlying, model, context, options, (payload) =>
      patchPayload({ payload, model, context, options }),
    );
  };
}

function isAnthropicThinkingEnabled(payload: Record<string, unknown>): boolean {
  const thinking = payload.thinking;
  if (!thinking || typeof thinking !== "object") {
    return false;
  }
  return (thinking as { type?: unknown }).type !== "disabled";
}

function assistantMessageHasAnthropicToolUse(message: Record<string, unknown>): boolean {
  if (Array.isArray(message.tool_calls) && message.tool_calls.length > 0) {
    return true;
  }
  const content = message.content;
  if (!Array.isArray(content)) {
    return false;
  }
  return content.some(
    (block) =>
      block &&
      typeof block === "object" &&
      ((block as { type?: unknown }).type === "tool_use" ||
        (block as { type?: unknown }).type === "toolCall"),
  );
}

function stripTrailingAssistantPrefillMessages(payload: Record<string, unknown>): number {
  if (!Array.isArray(payload.messages)) {
    return 0;
  }

  let stripped = 0;
  while (payload.messages.length > 0) {
    const finalMessage = payload.messages[payload.messages.length - 1];
    if (!finalMessage || typeof finalMessage !== "object") {
      break;
    }

    const message = finalMessage as Record<string, unknown>;
    if (message.role !== "assistant" || assistantMessageHasAnthropicToolUse(message)) {
      break;
    }

    payload.messages.pop();
    stripped += 1;
  }
  return stripped;
}

/** @deprecated Anthropic-family provider stream helper; do not use from third-party plugins. */
export function stripTrailingAnthropicAssistantPrefillWhenThinking(
  payload: Record<string, unknown>,
): number {
  if (!isAnthropicThinkingEnabled(payload)) {
    return 0;
  }
  return stripTrailingAssistantPrefillMessages(payload);
}

/** @deprecated Anthropic-family provider stream helper; do not use from third-party plugins. */
export function createAnthropicThinkingPrefillPayloadWrapper(
  baseStreamFn: StreamFn | undefined,
  onStripped?: (stripped: number) => void,
  wrapperOptions?: Parameters<typeof createPayloadPatchStreamWrapper>[2],
): StreamFn {
  return createPayloadPatchStreamWrapper(
    baseStreamFn,
    ({ payload }) => {
      const stripped = stripTrailingAnthropicAssistantPrefillWhenThinking(payload);
      if (stripped > 0) {
        onStripped?.(stripped);
      }
    },
    wrapperOptions,
  );
}

/** @deprecated OpenAI-compatible provider stream helper; do not use from third-party plugins. */
export type OpenAICompatibleThinkingLevel = ProviderWrapStreamFnContext["thinkingLevel"];

/** @deprecated OpenAI-compatible provider stream helper; do not use from third-party plugins. */
export function isOpenAICompatibleThinkingEnabled(params: {
  thinkingLevel: OpenAICompatibleThinkingLevel;
  options: Parameters<StreamFn>[2];
}): boolean {
  const options = (params.options ?? {}) as { reasoningEffort?: unknown; reasoning?: unknown };
  const raw = options.reasoningEffort ?? options.reasoning ?? params.thinkingLevel ?? "high";
  if (typeof raw !== "string") {
    return true;
  }
  const normalized = raw.trim().toLowerCase();
  return normalized !== "off" && normalized !== "none";
}

/** @deprecated DeepSeek provider stream helper; do not use from third-party plugins. */
export type DeepSeekV4ThinkingLevel = ProviderWrapStreamFnContext["thinkingLevel"];
/** @deprecated DeepSeek provider stream helper; do not use from third-party plugins. */
export type DeepSeekV4ReasoningEffort = "minimal" | "low" | "medium" | "high" | "xhigh" | "max";

function isDisabledDeepSeekV4ThinkingLevel(thinkingLevel: DeepSeekV4ThinkingLevel): boolean {
  const normalized = typeof thinkingLevel === "string" ? thinkingLevel.toLowerCase() : "";
  return normalized === "off" || normalized === "none";
}

function resolveDeepSeekV4ReasoningEffort(
  thinkingLevel: DeepSeekV4ThinkingLevel,
): DeepSeekV4ReasoningEffort {
  return thinkingLevel === "xhigh" || thinkingLevel === "max" ? "max" : "high";
}

function stripDeepSeekV4ReasoningContent(payload: Record<string, unknown>): void {
  if (!Array.isArray(payload.messages)) {
    return;
  }
  for (const message of payload.messages) {
    if (!message || typeof message !== "object") {
      continue;
    }
    delete (message as Record<string, unknown>).reasoning_content;
  }
}

function ensureDeepSeekV4AssistantReasoningContent(payload: Record<string, unknown>): void {
  if (!Array.isArray(payload.messages)) {
    return;
  }
  for (const message of payload.messages) {
    if (!message || typeof message !== "object") {
      continue;
    }
    const record = message as Record<string, unknown>;
    if (record.role !== "assistant") {
      continue;
    }
    if (!("reasoning_content" in record)) {
      record.reasoning_content = "";
    }
  }
}

/** @deprecated DeepSeek provider stream helper; do not use from third-party plugins. */
export function createDeepSeekV4OpenAICompatibleThinkingWrapper(params: {
  baseStreamFn: StreamFn | undefined;
  thinkingLevel: DeepSeekV4ThinkingLevel;
  shouldPatchModel: (model: Parameters<StreamFn>[0]) => boolean;
  resolveReasoningEffort?: (thinkingLevel: DeepSeekV4ThinkingLevel) => DeepSeekV4ReasoningEffort;
}): StreamFn | undefined {
  if (!params.baseStreamFn) {
    return undefined;
  }
  const underlying = params.baseStreamFn;
  const resolveReasoningEffort = params.resolveReasoningEffort ?? resolveDeepSeekV4ReasoningEffort;
  return (model, context, options) => {
    if (!params.shouldPatchModel(model)) {
      return underlying(model, context, options);
    }

    return streamWithPayloadPatch(underlying, model, context, options, (payload) => {
      if (isDisabledDeepSeekV4ThinkingLevel(params.thinkingLevel)) {
        payload.thinking = { type: "disabled" };
        delete payload.reasoning_effort;
        delete payload.reasoning;
        stripDeepSeekV4ReasoningContent(payload);
        return;
      }

      payload.thinking = { type: "enabled" };
      payload.reasoning_effort = resolveReasoningEffort(params.thinkingLevel);
      ensureDeepSeekV4AssistantReasoningContent(payload);
    });
  };
}

/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export type GoogleThinkingLevel = "MINIMAL" | "LOW" | "MEDIUM" | "HIGH";
/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export type GoogleThinkingInputLevel =
  | "off"
  | "minimal"
  | "low"
  | "medium"
  | "adaptive"
  | "high"
  | "max"
  | "xhigh";

// Gemini 2.5 Pro only works in thinking mode and rejects thinkingBudget=0 with
// "Budget 0 is invalid. This model only works in thinking mode."
/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export function isGoogleThinkingRequiredModel(modelId: string): boolean {
  return normalizeLowercaseStringOrEmpty(modelId).includes("gemini-2.5-pro");
}

/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export function isGoogleGemini25ThinkingBudgetModel(modelId: string): boolean {
  return /(?:^|\/)gemini-2\.5-/.test(normalizeLowercaseStringOrEmpty(modelId));
}

/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export function isGoogleGemini3ProModel(modelId: string): boolean {
  const normalized = normalizeLowercaseStringOrEmpty(modelId);
  return /(?:^|\/)gemini-(?:3(?:\.\d+)?-pro|pro-latest)(?:-|$)/.test(normalized);
}

/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export function isGoogleGemini3FlashModel(modelId: string): boolean {
  const normalized = normalizeLowercaseStringOrEmpty(modelId);
  return /(?:^|\/)gemini-(?:3(?:\.\d+)?-flash|flash(?:-lite)?-latest)(?:-|$)/.test(normalized);
}

/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export function isGoogleGemini3ThinkingLevelModel(modelId: string): boolean {
  return isGoogleGemini3ProModel(modelId) || isGoogleGemini3FlashModel(modelId);
}

/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export function resolveGoogleGemini3ThinkingLevel(params: {
  modelId?: string;
  thinkingLevel?: GoogleThinkingInputLevel;
  thinkingBudget?: number;
}): GoogleThinkingLevel | undefined {
  if (typeof params.modelId !== "string") {
    return undefined;
  }
  if (isGoogleGemini3ProModel(params.modelId)) {
    switch (params.thinkingLevel) {
      case "off":
      case "minimal":
      case "low":
        return "LOW";
      case "medium":
      case "high":
      case "max":
      case "xhigh":
        return "HIGH";
      case "adaptive":
        return undefined;
      case undefined:
        break;
    }
    if (typeof params.thinkingBudget === "number") {
      if (params.thinkingBudget < 0) {
        return undefined;
      }
      return params.thinkingBudget <= 2048 ? "LOW" : "HIGH";
    }
    return undefined;
  }
  if (!isGoogleGemini3FlashModel(params.modelId)) {
    return undefined;
  }
  switch (params.thinkingLevel) {
    case "off":
    case "minimal":
      return "MINIMAL";
    case "low":
      return "LOW";
    case "medium":
      return "MEDIUM";
    case "high":
    case "max":
    case "xhigh":
      return "HIGH";
    case "adaptive":
      return undefined;
    case undefined:
      break;
  }
  if (typeof params.thinkingBudget !== "number") {
    return undefined;
  }
  if (params.thinkingBudget < 0) {
    return undefined;
  }
  if (params.thinkingBudget <= 0) {
    return "MINIMAL";
  }
  if (params.thinkingBudget <= 2048) {
    return "LOW";
  }
  if (params.thinkingBudget <= 8192) {
    return "MEDIUM";
  }
  return "HIGH";
}

/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export function stripInvalidGoogleThinkingBudget(params: {
  thinkingConfig: Record<string, unknown>;
  modelId?: string;
}): boolean {
  if (
    params.thinkingConfig.thinkingBudget !== 0 ||
    typeof params.modelId !== "string" ||
    !isGoogleThinkingRequiredModel(params.modelId)
  ) {
    return false;
  }
  delete params.thinkingConfig.thinkingBudget;
  return true;
}

function isGemma4Model(modelId: string): boolean {
  return normalizeLowercaseStringOrEmpty(modelId).startsWith("gemma-4");
}

function mapThinkLevelToGemma4ThinkingLevel(
  thinkingLevel?: GoogleThinkingInputLevel,
): "MINIMAL" | "HIGH" | undefined {
  switch (thinkingLevel) {
    case "off":
      return undefined;
    case "minimal":
    case "low":
      return "MINIMAL";
    case "medium":
    case "adaptive":
    case "high":
    case "max":
    case "xhigh":
      return "HIGH";
    default:
      return undefined;
  }
}

function normalizeGemma4ThinkingLevel(value: unknown): "MINIMAL" | "HIGH" | undefined {
  if (typeof value !== "string") {
    return undefined;
  }
  switch (value.trim().toUpperCase()) {
    case "MINIMAL":
    case "LOW":
      return "MINIMAL";
    case "MEDIUM":
    case "HIGH":
      return "HIGH";
    default:
      return undefined;
  }
}

/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export function sanitizeGoogleThinkingPayload(params: {
  payload: unknown;
  modelId?: string;
  thinkingLevel?: GoogleThinkingInputLevel;
}): void {
  if (!params.payload || typeof params.payload !== "object") {
    return;
  }
  const payloadObj = params.payload as Record<string, unknown>;
  sanitizeGoogleThinkingConfigContainer({
    container: payloadObj.config,
    modelId: params.modelId,
    thinkingLevel: params.thinkingLevel,
  });
  sanitizeGoogleThinkingConfigContainer({
    container: payloadObj.generationConfig,
    modelId: params.modelId,
    thinkingLevel: params.thinkingLevel,
  });
}

function sanitizeGoogleThinkingConfigContainer(params: {
  container: unknown;
  modelId?: string;
  thinkingLevel?: GoogleThinkingInputLevel;
}): void {
  if (!params.container || typeof params.container !== "object") {
    return;
  }
  const configObj = params.container as Record<string, unknown>;
  const thinkingConfig = configObj.thinkingConfig;
  if (!thinkingConfig || typeof thinkingConfig !== "object") {
    return;
  }
  const thinkingConfigObj = thinkingConfig as Record<string, unknown>;

  if (typeof params.modelId === "string" && isGemma4Model(params.modelId)) {
    const normalizedThinkingLevel = normalizeGemma4ThinkingLevel(thinkingConfigObj.thinkingLevel);
    const explicitMappedLevel = mapThinkLevelToGemma4ThinkingLevel(params.thinkingLevel);
    const disabledViaBudget =
      typeof thinkingConfigObj.thinkingBudget === "number" && thinkingConfigObj.thinkingBudget <= 0;
    const hadThinkingBudget = thinkingConfigObj.thinkingBudget !== undefined;
    delete thinkingConfigObj.thinkingBudget;

    if (
      params.thinkingLevel === "off" ||
      (disabledViaBudget && explicitMappedLevel === undefined && !normalizedThinkingLevel)
    ) {
      delete thinkingConfigObj.thinkingLevel;
      if (Object.keys(thinkingConfigObj).length === 0) {
        delete configObj.thinkingConfig;
      }
      return;
    }

    const mappedLevel =
      explicitMappedLevel ?? normalizedThinkingLevel ?? (hadThinkingBudget ? "MINIMAL" : undefined);

    if (mappedLevel) {
      thinkingConfigObj.thinkingLevel = mappedLevel;
    }
    return;
  }

  const thinkingBudget = thinkingConfigObj.thinkingBudget;

  if (
    params.thinkingLevel === "adaptive" &&
    typeof params.modelId === "string" &&
    isGoogleGemini25ThinkingBudgetModel(params.modelId)
  ) {
    delete thinkingConfigObj.thinkingLevel;
    thinkingConfigObj.thinkingBudget = -1;
    return;
  }

  if (
    params.thinkingLevel === "adaptive" &&
    typeof params.modelId === "string" &&
    isGoogleGemini3ThinkingLevelModel(params.modelId)
  ) {
    delete thinkingConfigObj.thinkingBudget;
    delete thinkingConfigObj.thinkingLevel;
    if (Object.keys(thinkingConfigObj).length === 0) {
      delete configObj.thinkingConfig;
    }
    return;
  }

  if (typeof params.modelId === "string" && isGoogleGemini3ThinkingLevelModel(params.modelId)) {
    const mappedLevel = resolveGoogleGemini3ThinkingLevel({
      modelId: params.modelId,
      thinkingLevel: params.thinkingLevel,
      thinkingBudget: typeof thinkingBudget === "number" ? thinkingBudget : undefined,
    });
    delete thinkingConfigObj.thinkingBudget;
    if (mappedLevel) {
      thinkingConfigObj.thinkingLevel = mappedLevel;
    }
    if (Object.keys(thinkingConfigObj).length === 0) {
      delete configObj.thinkingConfig;
    }
    return;
  }

  if (
    stripInvalidGoogleThinkingBudget({ thinkingConfig: thinkingConfigObj, modelId: params.modelId })
  ) {
    if (Object.keys(thinkingConfigObj).length === 0) {
      delete configObj.thinkingConfig;
    }
    return;
  }

  if (typeof thinkingBudget !== "number" || thinkingBudget >= 0) {
    return;
  }

  // pi-ai can emit thinkingBudget=-1 for some Google model IDs; a negative budget
  // is invalid for Google-compatible backends and can lead to malformed handling.
  delete thinkingConfigObj.thinkingBudget;
  if (Object.keys(thinkingConfigObj).length === 0) {
    delete configObj.thinkingConfig;
  }
}

/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export function createGoogleThinkingPayloadWrapper(
  baseStreamFn: StreamFn | undefined,
  thinkingLevel?: GoogleThinkingInputLevel,
): StreamFn {
  return createPayloadPatchStreamWrapper(baseStreamFn, ({ payload, model }) => {
    if (model.api === "google-generative-ai") {
      sanitizeGoogleThinkingPayload({
        payload,
        modelId: model.id,
        thinkingLevel,
      });
    }
  });
}

/** @deprecated Google provider-owned stream helper; do not use from third-party plugins. */
export function createGoogleThinkingStreamWrapper(
  ctx: ProviderWrapStreamFnContext,
): NonNullable<ProviderWrapStreamFnContext["streamFn"]> {
  return createGoogleThinkingPayloadWrapper(ctx.streamFn, ctx.thinkingLevel);
}

export {
  applyAnthropicPayloadPolicyToParams,
  resolveAnthropicPayloadPolicy,
} from "../agents/anthropic-payload-policy.js";
export { applyAnthropicEphemeralCacheControlMarkers } from "../agents/pi-embedded-runner/anthropic-cache-control-payload.js";
export {
  createMoonshotThinkingWrapper,
  resolveMoonshotThinkingType,
} from "../agents/pi-embedded-runner/moonshot-thinking-stream-wrappers.js";
export { streamWithPayloadPatch };
export {
  createToolStreamWrapper,
  createZaiToolStreamWrapper,
} from "../agents/pi-embedded-runner/zai-stream-wrappers.js";