import { useState, useEffect, useCallback, useRef } from "react";
import imageCompression from "browser-image-compression";
import type { ACPClient } from "../src/acp/client";
import type { SessionUpdate, PermissionRequestPayload, PermissionOption, ContentBlock, ImageContent } from "../src/acp/types";
import type { ThreadEntry, ToolCallStatus, ToolCallData, UserMessageImage, UserMessageEntry, AssistantMessageEntry, ToolCallEntry, ChatInputMessage, PendingPermission } from "../src/lib/types";
import { ChatView } from "./chat/ChatView";
import { ChatInput } from "./chat/ChatInput";
import { PermissionPanel } from "./chat/PermissionPanel";
import { ModelSelectorPopover } from "./model-selector";
import { useCommands } from "../src/hooks/useCommands";

// Image compression options
// Claude API has a 5MB limit, so we target 2MB to be safe
const IMAGE_COMPRESSION_OPTIONS = {
  maxSizeMB: 2,           // Max output size in MB
  maxWidthOrHeight: 2048, // Max dimension (scales proportionally, no cropping)
  useWebWorker: true,     // Non-blocking compression
  fileType: "image/jpeg" as const, // Convert to JPEG for better compression
};

// Convert data URL to Blob without using fetch()
// This is critical for Chrome extensions where fetch(dataUrl) violates CSP
function dataUrlToBlob(dataUrl: string): Blob {
  // Parse the data URL: data:[<mediatype>][;base64],<data>
  const commaIndex = dataUrl.indexOf(",");
  if (commaIndex === -1) {
    throw new Error("Invalid data URL: missing comma separator");
  }

  const header = dataUrl.slice(0, commaIndex);
  const base64Data = dataUrl.slice(commaIndex + 1);

  // Extract MIME type from header (e.g., "data:image/png;base64")
  const mimeMatch = header.match(/^data:([^;,]+)/);
  const mimeType = mimeMatch ? mimeMatch[1] : "application/octet-stream";

  // Decode base64 to binary
  const binaryString = atob(base64Data);
  const bytes = new Uint8Array(binaryString.length);
  for (let i = 0; i < binaryString.length; i++) {
    bytes[i] = binaryString.charCodeAt(i);
  }

  return new Blob([bytes], { type: mimeType });
}

import { Plus } from "lucide-react";
import { Button } from "./ui/button";
import {
  Tooltip,
  TooltipContent,
  TooltipTrigger,
} from "./ui/tooltip";

// =============================================================================
// Type Definitions - imported from shared types module
// =============================================================================

interface ChatInterfaceProps {
  client: ACPClient;
}

// =============================================================================
// Helper Functions
// =============================================================================

// Map ACP status string to our status type
function mapToolStatus(status: string): ToolCallStatus {
  if (status === "completed") return "complete";
  if (status === "failed") return "error";
  return "running";
}

// Find tool call index in entries (search from end, like Zed)
function findToolCallIndex(entries: ThreadEntry[], toolCallId: string): number {
  for (let i = entries.length - 1; i >= 0; i--) {
    const entry = entries[i];
    if (entry && entry.type === "tool_call" && entry.toolCall.id === toolCallId) {
      return i;
    }
  }
  return -1;
}

// =============================================================================
// ChatInterface Component
// =============================================================================

export function ChatInterface({ client }: ChatInterfaceProps) {
  // Flat list of entries (like Zed's entries: Vec<AgentThreadEntry>)
  const [entries, setEntries] = useState<ThreadEntry[]>([]);
  const [isLoading, setIsLoading] = useState(false);
  const [sessionReady, setSessionReady] = useState(false);
  const [activeSessionId, setActiveSessionId] = useState<string | null>(null);
  const activeSessionIdRef = useRef<string | null>(null);
  const [errorMessage, setErrorMessage] = useState<string | null>(null);
  const errorTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
  // Reference: Zed's supports_images() checks prompt_capabilities.image
  const [supportsImages, setSupportsImages] = useState(false);
  const { commands: availableCommands } = useCommands(client);

  useEffect(() => {
    activeSessionIdRef.current = activeSessionId;
  }, [activeSessionId]);

  const resetThreadState = useCallback(() => {
    setEntries([]);
    setIsLoading(false);
    setSessionReady(false);
  }, []);

  const activateSession = useCallback((sessionId: string, options?: { resetEntries?: boolean }) => {
    const shouldResetEntries = options?.resetEntries ?? true;
    if (shouldResetEntries) {
      setEntries([]);
      setIsLoading(false);
    }
    setActiveSessionId(sessionId);
    setSessionReady(true);
    setSupportsImages(client.supportsImages);
    console.log("[ChatInterface] Active session:", sessionId, "supportsImages:", client.supportsImages);
  }, [client]);

  // =============================================================================
  // Permission Request Handler
  // =============================================================================
  const handlePermissionRequest = useCallback((request: PermissionRequestPayload) => {
    if (activeSessionIdRef.current && request.sessionId !== activeSessionIdRef.current) {
      return;
    }
    console.log("[ChatInterface] Permission request:", request);

    setEntries((prev) => {
      // Find matching tool call (search from end)
      const toolCallIndex = findToolCallIndex(prev, request.toolCall.toolCallId);

      if (toolCallIndex >= 0) {
        // Update existing tool call's status
        return prev.map((entry, index) => {
          if (index !== toolCallIndex) return entry;
          if (entry.type !== "tool_call") return entry;
          if (entry.toolCall.status !== "running") return entry;

          return {
            type: "tool_call",
            toolCall: {
              ...entry.toolCall,
              status: "waiting_for_confirmation" as const,
              permissionRequest: {
                requestId: request.requestId,
                options: request.options,
              },
            },
          };
        });
      } else {
        // No matching tool call - create standalone permission request as new entry
        console.log("[ChatInterface] No matching tool call, creating standalone permission request");

        const permissionToolCall: ToolCallEntry = {
          type: "tool_call",
          toolCall: {
            id: request.toolCall.toolCallId,
            title: request.toolCall.title || "Permission Request",
            status: "waiting_for_confirmation",
            permissionRequest: {
              requestId: request.requestId,
              options: request.options,
            },
            isStandalonePermission: true,
          },
        };

        return [...prev, permissionToolCall];
      }
    });
  }, []);

  // =============================================================================
  // Session Update Handler (Zed-style: check last entry type)
  // =============================================================================
  const handleSessionUpdate = useCallback((sessionId: string, update: SessionUpdate) => {
    if (activeSessionIdRef.current && sessionId !== activeSessionIdRef.current) {
      return;
    }

    // Handle agent message chunk
    if (update.sessionUpdate === "agent_message_chunk") {
      const text = update.content.type === "text" && update.content.text ? update.content.text : "";
      if (!text) return;

      setEntries((prev) => {
        const lastEntry = prev[prev.length - 1];

        // If last entry is AssistantMessage, append to it
        if (lastEntry?.type === "assistant_message") {
          const lastChunk = lastEntry.chunks[lastEntry.chunks.length - 1];

          // If last chunk is same type (message), append text
          if (lastChunk?.type === "message") {
            return [
              ...prev.slice(0, -1),
              {
                ...lastEntry,
                chunks: [
                  ...lastEntry.chunks.slice(0, -1),
                  { type: "message", text: lastChunk.text + text },
                ],
              },
            ];
          }

          // Otherwise add new message chunk
          return [
            ...prev.slice(0, -1),
            {
              ...lastEntry,
              chunks: [...lastEntry.chunks, { type: "message", text }],
            },
          ];
        }

        // Create new AssistantMessage entry
        const newEntry: AssistantMessageEntry = {
          type: "assistant_message",
          id: `assistant-${Date.now()}`,
          chunks: [{ type: "message", text }],
        };
        return [...prev, newEntry];
      });
    }
    // Handle agent thought chunk (NEW - was missing before)
    else if (update.sessionUpdate === "agent_thought_chunk") {
      const text = update.content.type === "text" && update.content.text ? update.content.text : "";
      if (!text) return;

      setEntries((prev) => {
        const lastEntry = prev[prev.length - 1];

        // If last entry is AssistantMessage, append to it
        if (lastEntry?.type === "assistant_message") {
          const lastChunk = lastEntry.chunks[lastEntry.chunks.length - 1];

          // If last chunk is same type (thought), append text
          if (lastChunk?.type === "thought") {
            return [
              ...prev.slice(0, -1),
              {
                ...lastEntry,
                chunks: [
                  ...lastEntry.chunks.slice(0, -1),
                  { type: "thought", text: lastChunk.text + text },
                ],
              },
            ];
          }

          // Otherwise add new thought chunk
          return [
            ...prev.slice(0, -1),
            {
              ...lastEntry,
              chunks: [...lastEntry.chunks, { type: "thought", text }],
            },
          ];
        }

        // Create new AssistantMessage entry with thought
        const newEntry: AssistantMessageEntry = {
          type: "assistant_message",
          id: `assistant-${Date.now()}`,
          chunks: [{ type: "thought", text }],
        };
        return [...prev, newEntry];
      });
    }
    // Handle user message chunk (NEW - was missing before)
    else if (update.sessionUpdate === "user_message_chunk") {
      const text = update.content.type === "text" && update.content.text ? update.content.text : "";
      if (!text) return;

      setEntries((prev) => {
        const lastEntry = prev[prev.length - 1];

        // If last entry is UserMessage, append to it
        if (lastEntry?.type === "user_message") {
          return [
            ...prev.slice(0, -1),
            {
              ...lastEntry,
              content: lastEntry.content + text,
            },
          ];
        }

        // Create new UserMessage entry
        const newEntry: UserMessageEntry = {
          type: "user_message",
          id: `user-${Date.now()}`,
          content: text,
        };
        return [...prev, newEntry];
      });
    }
    // Handle tool call (UPSERT - update if exists, create if not)
    else if (update.sessionUpdate === "tool_call") {
      const toolCallData: ToolCallData = {
        id: update.toolCallId,
        title: update.title,
        status: mapToolStatus(update.status),
        content: update.content,
        rawInput: update.rawInput,
        rawOutput: update.rawOutput,
      };

      setEntries((prev) => {
        // UPSERT: Check if tool call already exists
        const existingIndex = findToolCallIndex(prev, update.toolCallId);

        if (existingIndex >= 0) {
          // UPDATE existing tool call
          return prev.map((entry, index) => {
            if (index !== existingIndex) return entry;
            if (entry.type !== "tool_call") return entry;

            return {
              type: "tool_call",
              toolCall: {
                ...entry.toolCall,
                ...toolCallData,
              },
            };
          });
        }

        // CREATE new tool call entry
        const newEntry: ToolCallEntry = {
          type: "tool_call",
          toolCall: toolCallData,
        };
        return [...prev, newEntry];
      });
    }
    // Handle tool call update (partial update)
    else if (update.sessionUpdate === "tool_call_update") {
      setEntries((prev) => {
        const existingIndex = findToolCallIndex(prev, update.toolCallId);

        if (existingIndex < 0) {
          // Tool call not found - create a failed tool call entry (like Zed)
          console.warn(`[ChatInterface] Tool call not found for update: ${update.toolCallId}`);
          const failedEntry: ToolCallEntry = {
            type: "tool_call",
            toolCall: {
              id: update.toolCallId,
              title: update.title || "Tool call not found",
              status: "error",
              content: [{ type: "content", content: { type: "text", text: "Tool call not found" } }],
            },
          };
          return [...prev, failedEntry];
        }

        return prev.map((entry, index) => {
          if (index !== existingIndex) return entry;
          if (entry.type !== "tool_call") return entry;

          const newStatus = update.status ? mapToolStatus(update.status) : entry.toolCall.status;
          const mergedContent = update.content
            ? [...(entry.toolCall.content || []), ...update.content]
            : entry.toolCall.content;

          return {
            type: "tool_call",
            toolCall: {
              ...entry.toolCall,
              status: newStatus,
              ...(update.title && { title: update.title }),
              content: mergedContent,
              ...(update.rawInput && { rawInput: update.rawInput }),
              ...(update.rawOutput && { rawOutput: update.rawOutput }),
            },
          };
        });
      });
    }
  }, []);

  // =============================================================================
  // Setup Effect
  // =============================================================================
  useEffect(() => {
    client.setSessionCreatedHandler((sessionId) => {
      console.log("[ChatInterface] Session created:", sessionId);
      activateSession(sessionId);
    });

    client.setSessionLoadedHandler((sessionId) => {
      console.log("[ChatInterface] Session loaded/resumed:", sessionId);
      activateSession(sessionId, { resetEntries: false });
    });

    client.setSessionSwitchingHandler((sessionId) => {
      console.log("[ChatInterface] Switching to session:", sessionId);
      setActiveSessionId(sessionId);
      resetThreadState();
    });

    client.setSessionUpdateHandler((sessionId: string, update: SessionUpdate) => {
      handleSessionUpdate(sessionId, update);
    });

    client.setPromptCompleteHandler((stopReason) => {
      console.log("[ChatInterface] Prompt complete:", stopReason);
      // Always set isLoading=false when prompt completes
      // This includes stopReason="cancelled" (which is the expected response after client.cancel())
      // Note: Tool calls are already marked as "canceled" in handleCancel before this fires
      setIsLoading(false);
    });

    client.setPermissionRequestHandler(handlePermissionRequest);

    client.setErrorMessageHandler((msg) => {
      console.error("[ChatInterface] Agent error:", msg);
      setErrorMessage(msg);
      // Clear any existing timer
      if (errorTimerRef.current) clearTimeout(errorTimerRef.current);
      // Auto-clear after 5 seconds
      errorTimerRef.current = setTimeout(() => setErrorMessage(null), 5000);
    });

    // Create session
    client.createSession();
    return () => {
      if (errorTimerRef.current) clearTimeout(errorTimerRef.current);
      client.setSessionCreatedHandler(() => {});
      client.setSessionLoadedHandler(() => {});
      client.setSessionSwitchingHandler(null);
      client.setSessionUpdateHandler(() => {});
      client.setPromptCompleteHandler(() => {});
      client.setPermissionRequestHandler(() => {});
      client.setErrorMessageHandler(() => {});
    };
  }, [activateSession, client, handlePermissionRequest, handleSessionUpdate, resetThreadState]);

  // =============================================================================
  // User Actions
  // =============================================================================

  // Reference: Zed's ConnectionView.reset() + set_server_state() + _external_thread()
  // Creates a new session by clearing current state and calling new_session
  // This is the core of Zed's NewThread action
  const handleNewSession = useCallback(() => {
    console.log("[ChatInterface] Creating new session...");

    // Reference: Zed's set_server_state() calls close_all_sessions() before setting new state
    // Cancel any ongoing request before creating new session
    if (isLoading) {
      client.cancel();
    }

    // 1. Clear all entries (like Zed's set_server_state which creates new view)
    resetThreadState();
    setActiveSessionId(null);

    // 3. Create new session (like Zed's initial_state -> connection.new_session())
    // The session_created handler will set sessionReady=true when ready
    client.createSession();
  }, [client, isLoading, resetThreadState]);

  // Cancel handler - matches Zed's cancel() logic in acp_thread.rs
  // 1. Mark all pending/running/waiting_for_confirmation tool calls as canceled
  // 2. Send cancel notification to agent
  // 3. Do NOT set isLoading=false here - wait for prompt_complete with stopReason="cancelled"
  const handleCancel = () => {
    console.log("[ChatInterface] Cancel requested");

    // Like Zed: iterate all entries, mark Pending/WaitingForConfirmation/InProgress tool calls as Canceled
    setEntries((prev) =>
      prev.map((entry) => {
        if (entry.type !== "tool_call") return entry;

        // Check if status should be canceled (matches Zed's logic)
        const shouldCancel =
          entry.toolCall.status === "running" ||
          entry.toolCall.status === "waiting_for_confirmation";

        if (!shouldCancel) return entry;

        console.log("[ChatInterface] Marking tool call as canceled:", entry.toolCall.id);
        return {
          type: "tool_call",
          toolCall: {
            ...entry.toolCall,
            status: "canceled" as ToolCallStatus,
            permissionRequest: undefined, // Clear any pending permission request
          },
        };
      }),
    );

    // Send cancel notification to server (which forwards to agent)
    client.cancel();
    // Note: Do NOT set isLoading=false here!
    // Wait for prompt_complete with stopReason="cancelled" from the agent
  };

  const handlePermissionResponse = useCallback((requestId: string, optionId: string | null, optionKind: PermissionOption["kind"] | null) => {
    console.log("[ChatInterface] Permission response:", { requestId, optionId, optionKind });
    client.respondToPermission(requestId, optionId);

    // Determine new status based on option kind
    const isRejected = optionKind === "reject_once" || optionKind === "reject_always" || optionId === null;

    // Update the tool call status in entries
    setEntries((prev) =>
      prev.map((entry) => {
        if (entry.type !== "tool_call") return entry;
        if (entry.toolCall.permissionRequest?.requestId !== requestId) return entry;

        // For standalone permission requests, mark as complete immediately when approved
        // For regular tool calls, mark as running (agent will update to complete later)
        let newStatus: ToolCallStatus;
        if (isRejected) {
          newStatus = "rejected";
        } else if (entry.toolCall.isStandalonePermission) {
          newStatus = "complete";
        } else {
          newStatus = "running";
        }

        return {
          type: "tool_call",
          toolCall: {
            ...entry.toolCall,
            status: newStatus,
            permissionRequest: undefined,
            isStandalonePermission: undefined,
          },
        };
      }),
    );
  }, [client]);

  // =============================================================================
  // Render
  // =============================================================================

  // Collect pending permissions from tool call entries
  const pendingPermissions: PendingPermission[] = entries
    .filter((e): e is ToolCallEntry => e.type === "tool_call" && e.toolCall.status === "waiting_for_confirmation" && !!e.toolCall.permissionRequest)
    .map((e) => ({
      requestId: e.toolCall.permissionRequest!.requestId,
      toolName: e.toolCall.title,
      toolInput: e.toolCall.rawInput || {},
      description: e.toolCall.title,
      options: e.toolCall.permissionRequest!.options,
    }));

  // Handle permission respond for unified PermissionPanel
  const handlePermissionPanelRespond = useCallback((requestId: string, approved: boolean) => {
    const kind = approved ? "accept_once" : "reject_once";
    handlePermissionResponse(requestId, null, kind as PermissionOption["kind"] | null);
  }, [handlePermissionResponse]);

  // Handle ChatInput submit — convert ChatInputMessage to ContentBlock[]
  const handleChatInputSubmit = useCallback(async (message: ChatInputMessage) => {
    const text = message.text.trim();
    const images = message.images || [];

    if ((!text && images.length === 0) || isLoading || !sessionReady) return;

    const contentBlocks: ContentBlock[] = [];

    if (text) {
      contentBlocks.push({ type: "text", text });
    }

    // Convert images to ContentBlock
    const userImages: UserMessageImage[] = [];

    for (const img of images) {
      try {
        const dataUrl = `data:${img.mimeType};base64,${img.data}`;
        let blob: Blob;
        if (dataUrl.startsWith("data:")) {
          blob = dataUrlToBlob(dataUrl);
        } else {
          const response = await fetch(dataUrl);
          blob = await response.blob();
        }

        let finalBlob: Blob = blob;
        let finalMimeType = img.mimeType;

        if (blob.size > 2 * 1024 * 1024) {
          const imageFile = new File([blob], "image.jpg", { type: blob.type });
          finalBlob = await imageCompression(imageFile, IMAGE_COMPRESSION_OPTIONS);
          finalMimeType = "image/jpeg";
        }

        const base64Data = await new Promise<string>((resolve, reject) => {
          const reader = new FileReader();
          reader.onloadend = () => {
            const result = reader.result as string;
            const commaIndex = result.indexOf(",");
            resolve(commaIndex >= 0 ? result.slice(commaIndex + 1) : result);
          };
          reader.onerror = () => reject(new Error("FileReader error: " + reader.error?.message));
          reader.readAsDataURL(finalBlob);
        });

        const imageContent: ImageContent = {
          type: "image",
          mimeType: finalMimeType,
          data: base64Data,
        };
        contentBlocks.push(imageContent);

        userImages.push({
          mimeType: finalMimeType,
          data: base64Data,
        });
      } catch (error) {
        console.error("[ChatInterface] Failed to process image:", error);
      }
    }

    if (contentBlocks.length === 0) return;

    // Add user message entry
    const userEntry: UserMessageEntry = {
      type: "user_message",
      id: `user-${Date.now()}`,
      content: text,
      images: userImages.length > 0 ? userImages : undefined,
    };
    setEntries((prev) => [...prev, userEntry]);
    setIsLoading(true);

    try {
      await client.sendPrompt(contentBlocks);
    } catch (error) {
      console.error("[ChatInterface] Failed to send prompt:", error);
      setIsLoading(false);
    }
  }, [isLoading, sessionReady, client]);

  return (
    <div className="flex flex-col h-full">
      {/* Chat messages — unified ChatView */}
      <ChatView
        entries={entries}
        isLoading={isLoading && !sessionReady ? false : isLoading}
        onPermissionRespond={(requestId, optionId, optionKind) => {
          handlePermissionResponse(requestId, optionId, optionKind as PermissionOption["kind"] | null);
        }}
        emptyTitle={sessionReady ? "开始对话" : undefined}
        emptyDescription={sessionReady ? "输入消息开始与 ACP agent 聊天" : undefined}
      />

      {/* Permission panel — fixed above input */}
      <PermissionPanel
        requests={pendingPermissions}
        onRespond={handlePermissionPanelRespond}
      />

      {/* Error banner */}
      {errorMessage && (
        <div className="mx-auto max-w-3xl w-full px-4 pb-1">
          <div className="rounded-lg bg-red-50 dark:bg-red-900/20 border border-red-200 dark:border-red-800 px-3 py-2 text-sm text-red-700 dark:text-red-300 flex items-center justify-between">
            <span>{errorMessage}</span>
            <button
              type="button"
              onClick={() => setErrorMessage(null)}
              className="ml-2 text-red-500 hover:text-red-700 dark:text-red-400 dark:hover:text-red-200 flex-shrink-0"
            >
              {"\u00D7"}
            </button>
          </div>
        </div>
      )}

      {/* Model selector + New thread + ChatInput */}
      <div className="flex-shrink-0">
        <div className="max-w-3xl mx-auto w-full px-3 sm:px-4 pb-1 flex items-center justify-between">
          <ModelSelectorPopover client={client} />
          {entries.length > 0 && (
            <Tooltip>
              <TooltipTrigger asChild>
                <Button
                  variant="ghost"
                  size="sm"
                  className="h-7 text-xs text-text-muted hover:text-brand font-display gap-1"
                  onClick={handleNewSession}
                >
                  <Plus className="h-3 w-3" />
                  新会话
                </Button>
              </TooltipTrigger>
              <TooltipContent>New Thread</TooltipContent>
            </Tooltip>
          )}
        </div>
        <ChatInput
          onSubmit={handleChatInputSubmit}
          isLoading={isLoading}
          onInterrupt={handleCancel}
          disabled={!sessionReady}
          placeholder={sessionReady ? "给 Claude 发送消息…" : "等待会话..."}
          supportsImages={supportsImages}
          commands={availableCommands.length > 0 ? availableCommands : undefined}
        />
      </div>
    </div>
  );
}