import { TRPCError } from "@trpc/server";
import { loggedAiCall, parseAiError } from "../ai-client.js";
import { createAuditEntry } from "../lib/audit.js";
import { checkAiOutput } from "../lib/content-filter.js";
import { logger } from "../lib/logger.js";
import {
  AssistantApprovalStorageUnavailableError,
  createPendingAssistantApproval,
  toApprovalPayload,
} from "./assistant-approvals.js";
import {
  ASSISTANT_CONFIRMATION_PREFIX,
  parseToolArguments,
} from "./assistant-confirmation.js";
import {
  buildAssistantChatResponse,
  mergeInsights,
  type AssistantChatResponse,
} from "./assistant-chat-response.js";
import { buildAssistantInsight, type AssistantInsight } from "./assistant-insights.js";
import {
  executeTool,
  MUTATION_TOOLS,
  type ToolAction,
  type ToolContext,
} from "./assistant-tools.js";

type AssistantToolCall = {
  id: string;
  function: {
    name: string;
    arguments: string;
  };
};

type AssistantChoiceMessage = {
  content?: string | null;
  tool_calls?: AssistantToolCall[];
};

type AssistantCompletionResponse = {
  choices?: Array<{
    message?: AssistantChoiceMessage;
  }>;
};

type AssistantChatClient = {
  chat: {
    completions: {
      create(...args: any[]): Promise<unknown>;
    };
  };
};

export async function runAssistantToolLoop(input: {
  db: ToolContext["db"];
  dbUserId?: string | undefined;
  client: AssistantChatClient;
  provider: string;
  model: string;
  maxTokens: number;
  temperature: number;
  openaiMessages: Array<{ content?: unknown } & Record<string, unknown>>;
  availableTools: unknown[];
  toolCtx: ToolContext;
  userId: string;
  conversationId: string;
  collectedActions: ToolAction[];
  collectedInsights: AssistantInsight[];
  maxToolIterations: number;
}): Promise<AssistantChatResponse> {
  let collectedActions = input.collectedActions;
  let collectedInsights = input.collectedInsights;

  for (let i = 0; i < input.maxToolIterations; i++) {
    const response = await requestAssistantCompletion(input);
    const choice = response.choices?.[0];
    const msg = choice?.message;
    if (!msg) {
      throw new TRPCError({ code: "INTERNAL_SERVER_ERROR", message: "No response from AI" });
    }

    if (msg.tool_calls && msg.tool_calls.length > 0) {
      input.openaiMessages.push(msg);

      const toolResult = await handleAssistantToolCalls({
        db: input.db,
        dbUserId: input.dbUserId,
        openaiMessages: input.openaiMessages,
        toolCalls: msg.tool_calls,
        toolCtx: input.toolCtx,
        userId: input.userId,
        conversationId: input.conversationId,
        collectedActions,
        collectedInsights,
      });

      collectedActions = toolResult.collectedActions;
      collectedInsights = toolResult.collectedInsights;

      if (toolResult.response) {
        return toolResult.response;
      }

      continue;
    }

    return buildFinalAssistantResponse({
      db: input.db,
      dbUserId: input.dbUserId,
      content: msg.content,
      collectedActions,
      collectedInsights,
    });
  }

  return buildAssistantChatResponse({
    content: "I had to stop after too many tool calls. Please try a simpler question.",
    insights: collectedInsights,
    actions: collectedActions,
  });
}

async function requestAssistantCompletion(input: {
  client: AssistantChatClient;
  provider: string;
  model: string;
  maxTokens: number;
  temperature: number;
  openaiMessages: Array<{ content?: unknown } & Record<string, unknown>>;
  availableTools: unknown[];
}): Promise<AssistantCompletionResponse> {
  const msgLen = input.openaiMessages.reduce(
    (total, message) => total + (typeof message.content === "string" ? message.content.length : 0),
    0,
  );

  try {
    const response = await loggedAiCall(input.provider, input.model, msgLen, () =>
      input.client.chat.completions.create({
        model: input.model,
        messages: input.openaiMessages,
        tools: input.availableTools,
        max_completion_tokens: input.maxTokens,
        temperature: input.temperature,
      }),
    );
    return response as AssistantCompletionResponse;
  } catch (error) {
    throw new TRPCError({
      code: "INTERNAL_SERVER_ERROR",
      message: `AI error: ${parseAiError(error)}`,
    });
  }
}

async function handleAssistantToolCalls(input: {
  db: ToolContext["db"];
  dbUserId?: string | undefined;
  openaiMessages: Array<{ content?: unknown } & Record<string, unknown>>;
  toolCalls: AssistantToolCall[];
  toolCtx: ToolContext;
  userId: string;
  conversationId: string;
  collectedActions: ToolAction[];
  collectedInsights: AssistantInsight[];
}): Promise<{
  response: AssistantChatResponse | null;
  collectedActions: ToolAction[];
  collectedInsights: AssistantInsight[];
}> {
  let collectedActions = input.collectedActions;
  let collectedInsights = input.collectedInsights;

  for (const toolCall of input.toolCalls) {
    if (MUTATION_TOOLS.has(toolCall.function.name)) {
      try {
        const approval = await createPendingAssistantApproval(
          input.db,
          input.userId,
          input.conversationId,
          toolCall.function.name,
          toolCall.function.arguments,
        );

        void createAuditEntry({
          db: input.db,
          entityType: "AiToolExecution",
          entityId: toolCall.id,
          entityName: toolCall.function.name,
          action: "CREATE",
          source: "ai",
          summary: `AI tool blocked pending confirmation: ${toolCall.function.name}`,
          after: {
            approvalId: approval.id,
            params: parseToolArguments(toolCall.function.arguments),
            executed: false,
          },
          ...(input.dbUserId !== undefined ? { userId: input.dbUserId } : {}),
        });

        return {
          response: buildAssistantChatResponse({
            content: `${ASSISTANT_CONFIRMATION_PREFIX} ${approval.summary}. Bitte bestätigen.`,
            approval: toApprovalPayload(approval, "pending"),
            insights: collectedInsights,
            actions: collectedActions,
          }),
          collectedActions,
          collectedInsights,
        };
      } catch (error) {
        if (!(error instanceof AssistantApprovalStorageUnavailableError)) {
          throw error;
        }

        return {
          response: buildAssistantChatResponse({
            content: "Schreibende Assistant-Aktionen sind gerade nicht verfuegbar, weil der Bestaetigungsspeicher in der Datenbank fehlt. Bitte die CapaKraken-DB-Migration anwenden und dann erneut versuchen.",
            insights: collectedInsights,
            actions: collectedActions,
          }),
          collectedActions,
          collectedInsights,
        };
      }
    }

    const result = await executeTool(
      toolCall.function.name,
      toolCall.function.arguments,
      input.toolCtx,
    );

    const insight = buildAssistantInsight(toolCall.function.name, result.data);
    if (insight) {
      collectedInsights = mergeInsights(collectedInsights, insight);
    }

    if (result.action) {
      collectedActions = [...collectedActions, result.action];
    }

    input.openaiMessages.push({
      role: "tool",
      tool_call_id: toolCall.id,
      content: result.content,
    });

    let parsedArgs: Record<string, unknown> = {};
    try {
      parsedArgs = JSON.parse(toolCall.function.arguments) as Record<string, unknown>;
    } catch {
      parsedArgs = {};
    }

    void createAuditEntry({
      db: input.db,
      entityType: "AiToolExecution",
      entityId: toolCall.id,
      entityName: toolCall.function.name,
      action: "CREATE",
      source: "ai",
      summary: `AI executed tool: ${toolCall.function.name}`,
      after: { params: parsedArgs, executed: true },
      ...(input.dbUserId !== undefined ? { userId: input.dbUserId } : {}),
    });
  }

  return {
    response: null,
    collectedActions,
    collectedInsights,
  };
}

function buildFinalAssistantResponse(input: {
  db: ToolContext["db"];
  dbUserId?: string | undefined;
  content?: string | null | undefined;
  collectedActions: ToolAction[];
  collectedInsights: AssistantInsight[];
}): AssistantChatResponse {
  let finalContent = input.content ?? "I couldn't generate a response.";
  const contentCheck = checkAiOutput(finalContent);
  if (!contentCheck.clean) {
    logger.warn(
      { userId: input.dbUserId },
      "AI output contained sensitive content — redacted before delivery",
    );
    finalContent = contentCheck.redacted;
    void createAuditEntry({
      db: input.db,
      entityType: "SecurityAlert",
      entityId: crypto.randomUUID(),
      entityName: "AiOutputRedacted",
      action: "CREATE",
      source: "ai",
      summary: "AI output contained potentially sensitive content and was redacted",
      ...(input.dbUserId !== undefined ? { userId: input.dbUserId } : {}),
    });
  }

  return buildAssistantChatResponse({
    content: finalContent,
    insights: input.collectedInsights,
    actions: input.collectedActions,
  });
}