import { invoke } from "@tauri-apps/api/core";
import { listen } from "@tauri-apps/api/event";
import { ask } from "@tauri-apps/plugin-dialog";
import { useEffect, useRef, useState } from "react";
import Markdown from "react-markdown";
import { Prism as SyntaxHighlighter } from "react-syntax-highlighter";
import { oneDark } from "react-syntax-highlighter/dist/esm/styles/prism";
import type { Message, ProviderConfig } from "../types";

interface ChatProps {
	projectPath: string;
	onCloseProject: () => void;
}

export function Chat({ projectPath, onCloseProject }: ChatProps) {
	const [messages, setMessages] = useState<Message[]>([]);
	const [input, setInput] = useState("");
	const [loading, setLoading] = useState(false);
	const [model, setModel] = useState("llama3.1"); // Default local model
	const [enableTools, setEnableTools] = useState(true);
	const [availableModels, setAvailableModels] = useState<string[]>([]);
	const [claudeModels] = useState<string[]>([
		"claude-3-5-sonnet-20241022",
		"claude-3-5-haiku-20241022",
	]);
	const [streamingContent, setStreamingContent] = useState("");
	const [showApiKeyDialog, setShowApiKeyDialog] = useState(false);
	const [apiKeyInput, setApiKeyInput] = useState("");
	const messagesEndRef = useRef<HTMLDivElement>(null);
	const inputRef = useRef<HTMLInputElement>(null);
	const scrollContainerRef = useRef<HTMLDivElement>(null);
	const shouldAutoScrollRef = useRef(true);
	const lastScrollTopRef = useRef(0);
	const userScrolledUpRef = useRef(false);

	// Token estimation and context window tracking
	const estimateTokens = (text: string): number => {
		return Math.ceil(text.length / 4);
	};

	const getContextWindowSize = (modelName: string): number => {
		if (modelName.startsWith("claude-")) return 200000;
		if (modelName.includes("llama3")) return 8192;
		if (modelName.includes("qwen2.5")) return 32768;
		if (modelName.includes("deepseek")) return 16384;
		return 8192; // Default
	};

	const calculateContextUsage = (): {
		used: number;
		total: number;
		percentage: number;
	} => {
		let totalTokens = 0;

		// System prompts (approximate)
		totalTokens += 200;

		// All messages
		for (const msg of messages) {
			totalTokens += estimateTokens(msg.content);
			if (msg.tool_calls) {
				totalTokens += estimateTokens(JSON.stringify(msg.tool_calls));
			}
		}

		// Streaming content
		if (streamingContent) {
			totalTokens += estimateTokens(streamingContent);
		}

		const contextWindow = getContextWindowSize(model);
		const percentage = Math.round((totalTokens / contextWindow) * 100);

		return {
			used: totalTokens,
			total: contextWindow,
			percentage,
		};
	};

	const contextUsage = calculateContextUsage();

	const getContextEmoji = (percentage: number): string => {
		if (percentage >= 90) return "🔴";
		if (percentage >= 75) return "🟡";
		return "🟢";
	};

	useEffect(() => {
		invoke<string[]>("get_ollama_models")
			.then(async (models) => {
				if (models.length > 0) {
					// Sort models alphabetically (case-insensitive)
					const sortedModels = models.sort((a, b) =>
						a.toLowerCase().localeCompare(b.toLowerCase()),
					);
					setAvailableModels(sortedModels);

					// Check backend store for saved model
					try {
						const savedModel = await invoke<string | null>(
							"get_model_preference",
						);
						if (savedModel) {
							setModel(savedModel);
						} else if (models.length > 0) {
							setModel(models[0]);
						}
					} catch (e) {
						console.error(e);
					}
				}
			})
			.catch((err) => console.error(err));
		// eslint-disable-next-line react-hooks/exhaustive-deps
	}, []);

	useEffect(() => {
		const unlistenUpdatePromise = listen<Message[]>("chat:update", (event) => {
			setMessages(event.payload);
			setStreamingContent(""); // Clear streaming content when final update arrives
		});

		const unlistenTokenPromise = listen<string>("chat:token", (event) => {
			setStreamingContent((prev) => prev + event.payload);
		});

		return () => {
			unlistenUpdatePromise.then((unlisten) => unlisten());
			unlistenTokenPromise.then((unlisten) => unlisten());
		};
	}, []);

	const scrollToBottom = () => {
		const element = scrollContainerRef.current;
		if (element) {
			element.scrollTop = element.scrollHeight;
			lastScrollTopRef.current = element.scrollHeight;
		}
	};

	const handleScroll = () => {
		const element = scrollContainerRef.current;
		if (!element) return;

		const currentScrollTop = element.scrollTop;
		const isAtBottom =
			element.scrollHeight - element.scrollTop - element.clientHeight < 5;

		// Detect if user scrolled UP
		if (currentScrollTop < lastScrollTopRef.current) {
			userScrolledUpRef.current = true;
			shouldAutoScrollRef.current = false;
		}

		// If user scrolled back to bottom, re-enable auto-scroll
		if (isAtBottom) {
			userScrolledUpRef.current = false;
			shouldAutoScrollRef.current = true;
		}

		lastScrollTopRef.current = currentScrollTop;
	};

	// Smart auto-scroll: only scroll if user hasn't scrolled up
	// biome-ignore lint/correctness/useExhaustiveDependencies: We intentionally trigger on messages/streamingContent changes
	useEffect(() => {
		if (shouldAutoScrollRef.current && !userScrolledUpRef.current) {
			scrollToBottom();
		}
	}, [messages, streamingContent]);

	useEffect(() => {
		inputRef.current?.focus();
	}, []);

	const cancelGeneration = async () => {
		try {
			await invoke("cancel_chat");

			// Preserve any partial streaming content as a message
			if (streamingContent) {
				setMessages((prev) => [
					...prev,
					{ role: "assistant", content: streamingContent },
				]);
				setStreamingContent("");
			}

			setLoading(false);
		} catch (e) {
			console.error("Failed to cancel chat:", e);
		}
	};

	const sendMessage = async () => {
		if (!input.trim() || loading) return;

		// Check if using Claude and API key is required
		if (model.startsWith("claude-")) {
			const hasKey = await invoke<boolean>("get_anthropic_api_key_exists");
			if (!hasKey) {
				setShowApiKeyDialog(true);
				return;
			}
		}

		const userMsg: Message = { role: "user", content: input };
		const newHistory = [...messages, userMsg];

		setMessages(newHistory);
		setInput("");
		setLoading(true);
		setStreamingContent(""); // Clear any previous streaming content

		try {
			const config: ProviderConfig = {
				provider: model.startsWith("claude-") ? "anthropic" : "ollama",
				model: model,
				base_url: "http://localhost:11434",
				enable_tools: enableTools,
			};

			// Invoke backend chat command
			// We rely on 'chat:update' events to update the state in real-time
			await invoke("chat", {
				messages: newHistory,
				config: config,
			});
		} catch (e) {
			console.error(e);
			// Don't show error message if user cancelled
			const errorMessage = String(e);
			if (!errorMessage.includes("Chat cancelled by user")) {
				setMessages((prev) => [
					...prev,
					{ role: "assistant", content: `**Error:** ${e}` },
				]);
			}
		} finally {
			setLoading(false);
		}
	};

	const handleSaveApiKey = async () => {
		if (!apiKeyInput.trim()) return;

		try {
			await invoke("set_anthropic_api_key", { apiKey: apiKeyInput });
			setShowApiKeyDialog(false);
			setApiKeyInput("");
			// Retry sending the message
			sendMessage();
		} catch (e) {
			console.error("Failed to save API key:", e);
			alert(`Failed to save API key: ${e}`);
		}
	};

	const clearSession = async () => {
		const confirmed = await ask(
			"Are you sure? This will clear all messages and reset the conversation context.",
			{
				title: "New Session",
				kind: "warning",
			},
		);

		if (confirmed) {
			// Cancel any in-flight backend requests first
			try {
				await invoke("cancel_chat");
			} catch (e) {
				console.error("Failed to cancel chat:", e);
			}

			// Then clear frontend state
			setMessages([]);
			setStreamingContent("");
			setLoading(false);
		}
	};

	return (
		<div
			className="chat-container"
			style={{
				display: "flex",
				flexDirection: "column",
				height: "100%",
				backgroundColor: "#171717",
				color: "#ececec",
			}}
		>
			{/* Sticky Header */}
			<div
				style={{
					padding: "12px 24px",
					borderBottom: "1px solid #333",
					display: "flex",
					alignItems: "center",
					justifyContent: "space-between",
					background: "#171717",
					flexShrink: 0,
					fontSize: "0.9rem",
					color: "#ececec",
				}}
			>
				{/* Project Info */}
				<div
					style={{
						display: "flex",
						alignItems: "center",
						gap: "12px",
						overflow: "hidden",
						flex: 1,
						marginRight: "20px",
					}}
				>
					<div
						title={projectPath}
						style={{
							whiteSpace: "nowrap",
							overflow: "hidden",
							textOverflow: "ellipsis",
							fontWeight: "500",
							color: "#aaa",
							direction: "rtl",
							textAlign: "left",
							fontFamily: "monospace",
							fontSize: "0.85em",
						}}
					>
						{projectPath}
					</div>
					<button
						type="button"
						onClick={onCloseProject}
						style={{
							background: "transparent",
							border: "none",
							cursor: "pointer",
							color: "#999",
							fontSize: "0.8em",
							padding: "4px 8px",
							borderRadius: "4px",
						}}
						onMouseOver={(e) => {
							e.currentTarget.style.background = "#333";
						}}
						onMouseOut={(e) => {
							e.currentTarget.style.background = "transparent";
						}}
						onFocus={(e) => {
							e.currentTarget.style.background = "#333";
						}}
						onBlur={(e) => {
							e.currentTarget.style.background = "transparent";
						}}
					>
						✕
					</button>
				</div>

				{/* Model Controls */}
				<div style={{ display: "flex", alignItems: "center", gap: "16px" }}>
					{/* Context Usage Indicator */}
					<div
						style={{
							fontSize: "0.9em",
							color: "#ccc",
							whiteSpace: "nowrap",
						}}
						title={`Context: ${contextUsage.used.toLocaleString()} / ${contextUsage.total.toLocaleString()} tokens (${contextUsage.percentage}%)`}
					>
						{getContextEmoji(contextUsage.percentage)} {contextUsage.percentage}
						%
					</div>

					<button
						type="button"
						onClick={clearSession}
						style={{
							padding: "6px 12px",
							borderRadius: "99px",
							border: "none",
							fontSize: "0.85em",
							backgroundColor: "#2f2f2f",
							color: "#888",
							cursor: "pointer",
							outline: "none",
							transition: "all 0.2s",
						}}
						onMouseOver={(e) => {
							e.currentTarget.style.backgroundColor = "#3f3f3f";
							e.currentTarget.style.color = "#ccc";
						}}
						onMouseOut={(e) => {
							e.currentTarget.style.backgroundColor = "#2f2f2f";
							e.currentTarget.style.color = "#888";
						}}
						onFocus={(e) => {
							e.currentTarget.style.backgroundColor = "#3f3f3f";
							e.currentTarget.style.color = "#ccc";
						}}
						onBlur={(e) => {
							e.currentTarget.style.backgroundColor = "#2f2f2f";
							e.currentTarget.style.color = "#888";
						}}
					>
						🔄 New Session
					</button>
					{availableModels.length > 0 || claudeModels.length > 0 ? (
						<select
							value={model}
							onChange={(e) => {
								const newModel = e.target.value;
								setModel(newModel);
								invoke("set_model_preference", { model: newModel }).catch(
									console.error,
								);
							}}
							style={{
								padding: "6px 32px 6px 16px",
								borderRadius: "99px",
								border: "none",
								fontSize: "0.9em",
								backgroundColor: "#2f2f2f",
								color: "#ececec",
								cursor: "pointer",
								outline: "none",
								appearance: "none",
								WebkitAppearance: "none",
								backgroundImage: `url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23ececec%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E")`,
								backgroundRepeat: "no-repeat",
								backgroundPosition: "right 12px center",
								backgroundSize: "10px",
							}}
						>
							{claudeModels.length > 0 && (
								<optgroup label="Anthropic">
									{claudeModels.map((m) => (
										<option key={m} value={m}>
											{m}
										</option>
									))}
								</optgroup>
							)}
							{availableModels.length > 0 && (
								<optgroup label="Ollama">
									{availableModels.map((m) => (
										<option key={m} value={m}>
											{m}
										</option>
									))}
								</optgroup>
							)}
						</select>
					) : (
						<input
							value={model}
							onChange={(e) => {
								const newModel = e.target.value;
								setModel(newModel);
								invoke("set_model_preference", { model: newModel }).catch(
									console.error,
								);
							}}
							placeholder="Model"
							style={{
								padding: "6px 12px",
								borderRadius: "99px",
								border: "none",
								fontSize: "0.9em",
								background: "#2f2f2f",
								color: "#ececec",
								outline: "none",
							}}
						/>
					)}
					<label
						style={{
							display: "flex",
							alignItems: "center",
							gap: "6px",
							cursor: "pointer",
							fontSize: "0.9em",
							color: "#aaa",
						}}
						title="Allow the Agent to read/write files"
					>
						<input
							type="checkbox"
							checked={enableTools}
							onChange={(e) => setEnableTools(e.target.checked)}
							style={{ accentColor: "#000" }}
						/>
						<span>Tools</span>
					</label>
				</div>
			</div>

			{/* Messages Area */}
			<div
				ref={scrollContainerRef}
				onScroll={handleScroll}
				style={{
					flex: 1,
					overflowY: "auto",
					padding: "20px 0",
					display: "flex",
					flexDirection: "column",
					gap: "24px",
				}}
			>
				<div
					style={{
						maxWidth: "768px",
						margin: "0 auto",
						width: "100%",
						padding: "0 24px",
						display: "flex",
						flexDirection: "column",
						gap: "24px",
					}}
				>
					{messages.map((msg, idx) => (
						<div
							key={`msg-${idx}-${msg.role}-${msg.content.substring(0, 20)}`}
							style={{
								display: "flex",
								flexDirection: "column",
								alignItems: msg.role === "user" ? "flex-end" : "flex-start",
							}}
						>
							<div
								style={{
									maxWidth: "100%",
									padding: msg.role === "user" ? "10px 16px" : "0",
									borderRadius: msg.role === "user" ? "20px" : "0",
									background:
										msg.role === "user"
											? "#2f2f2f"
											: msg.role === "tool"
												? "#222"
												: "transparent",
									color: "#ececec",
									border: msg.role === "tool" ? "1px solid #333" : "none",
									fontFamily: msg.role === "tool" ? "monospace" : "inherit",
									fontSize: msg.role === "tool" ? "0.85em" : "1em",
									fontWeight: "500",
									whiteSpace: msg.role === "tool" ? "pre-wrap" : "normal",
									lineHeight: "1.6",
								}}
							>
								{msg.role === "user" ? (
									msg.content
								) : msg.role === "tool" ? (
									<details style={{ cursor: "pointer" }}>
										<summary
											style={{
												color: "#aaa",
												fontSize: "0.9em",
												marginBottom: "8px",
												listStyle: "none",
												display: "flex",
												alignItems: "center",
												gap: "6px",
											}}
										>
											<span style={{ fontSize: "0.8em" }}>▶</span>
											<span>
												Tool Output
												{msg.tool_call_id && ` (${msg.tool_call_id})`}
											</span>
										</summary>
										<pre
											style={{
												maxHeight: "300px",
												overflow: "auto",
												margin: 0,
												padding: "8px",
												background: "#1a1a1a",
												borderRadius: "4px",
												fontSize: "0.85em",
												whiteSpace: "pre-wrap",
												wordBreak: "break-word",
											}}
										>
											{msg.content}
										</pre>
									</details>
								) : (
									<div className="markdown-body">
										<Markdown
											components={{
												// react-markdown types are incompatible with strict typing
												// eslint-disable-next-line @typescript-eslint/no-explicit-any
												// biome-ignore lint/suspicious/noExplicitAny: react-markdown requires any for component props
												code: ({ className, children, ...props }: any) => {
													const match = /language-(\w+)/.exec(className || "");
													const isInline = !className;
													return !isInline && match ? (
														<SyntaxHighlighter
															// biome-ignore lint/suspicious/noExplicitAny: oneDark style types are incompatible
															style={oneDark as any}
															language={match[1]}
															PreTag="div"
														>
															{String(children).replace(/\n$/, "")}
														</SyntaxHighlighter>
													) : (
														<code className={className} {...props}>
															{children}
														</code>
													);
												},
											}}
										>
											{msg.content}
										</Markdown>
									</div>
								)}

								{/* Show Tool Calls if present */}
								{msg.tool_calls && (
									<div
										style={{
											marginTop: "12px",
											fontSize: "0.85em",
											color: "#aaa",
											display: "flex",
											flexDirection: "column",
											gap: "8px",
										}}
									>
										{msg.tool_calls.map((tc, i) => {
											// Parse arguments to extract key info
											let argsSummary = "";
											try {
												const args = JSON.parse(tc.function.arguments);
												const firstKey = Object.keys(args)[0];
												if (firstKey && args[firstKey]) {
													argsSummary = String(args[firstKey]);
													// Truncate if too long
													if (argsSummary.length > 50) {
														argsSummary = `${argsSummary.substring(0, 47)}...`;
													}
												}
											} catch (_e) {
												// If parsing fails, just show empty
											}

											return (
												<div
													key={`tool-${i}-${tc.function.name}`}
													style={{
														display: "flex",
														alignItems: "center",
														gap: "8px",
														fontFamily: "monospace",
													}}
												>
													<span style={{ color: "#888" }}>▶</span>
													<span
														style={{
															background: "#333",
															padding: "2px 6px",
															borderRadius: "4px",
														}}
													>
														{tc.function.name}
														{argsSummary && `(${argsSummary})`}
													</span>
												</div>
											);
										})}
									</div>
								)}
							</div>
						</div>
					))}
					{loading && streamingContent && (
						<div
							style={{
								display: "flex",
								flexDirection: "column",
								alignItems: "flex-start",
							}}
						>
							<div
								style={{
									maxWidth: "85%",
									padding: "16px 20px",
									borderRadius: "12px",
									background: "#262626",
									color: "#fff",
									border: "1px solid #404040",
									fontFamily: "system-ui, -apple-system, sans-serif",
									fontSize: "0.95rem",
									fontWeight: 400,
									whiteSpace: "pre-wrap",
									lineHeight: 1.6,
								}}
							>
								<Markdown
									components={{
										// react-markdown types are incompatible with strict typing
										// eslint-disable-next-line @typescript-eslint/no-explicit-any
										// biome-ignore lint/suspicious/noExplicitAny: react-markdown requires any for component props
										code: ({ className, children, ...props }: any) => {
											const match = /language-(\w+)/.exec(className || "");
											const isInline = !className;
											return !isInline && match ? (
												<SyntaxHighlighter
													// biome-ignore lint/suspicious/noExplicitAny: oneDark style types are incompatible
													style={oneDark as any}
													language={match[1]}
													PreTag="div"
												>
													{String(children).replace(/\n$/, "")}
												</SyntaxHighlighter>
											) : (
												<code className={className} {...props}>
													{children}
												</code>
											);
										},
									}}
								>
									{streamingContent}
								</Markdown>
							</div>
						</div>
					)}
					{loading && !streamingContent && (
						<div
							style={{
								alignSelf: "flex-start",
								color: "#888",
								fontSize: "0.9em",
								marginTop: "10px",
							}}
						>
							<span className="pulse">Thinking...</span>
						</div>
					)}
					<div ref={messagesEndRef} />
				</div>
			</div>

			{/* Input Area */}
			<div
				style={{
					padding: "24px",
					background: "#171717",
					display: "flex",
					justifyContent: "center",
				}}
			>
				<div
					style={{
						maxWidth: "768px",
						width: "100%",
						display: "flex",
						gap: "8px",
						alignItems: "center",
					}}
				>
					<input
						ref={inputRef}
						value={input}
						onChange={(e) => setInput(e.target.value)}
						onKeyDown={(e) => e.key === "Enter" && sendMessage()}
						placeholder="Send a message..."
						style={{
							flex: 1,
							padding: "14px 20px",
							borderRadius: "24px",
							border: "1px solid #333",
							outline: "none",
							fontSize: "1rem",
							fontWeight: "500",
							background: "#2f2f2f",
							color: "#ececec",
							boxShadow: "0 2px 6px rgba(0,0,0,0.02)",
						}}
					/>
					<button
						type="button"
						onClick={loading ? cancelGeneration : sendMessage}
						disabled={!loading && !input.trim()}
						style={{
							background: "#ececec",
							color: "black",
							border: "none",
							borderRadius: "50%",
							width: "32px",
							height: "32px",
							display: "flex",
							alignItems: "center",
							justifyContent: "center",
							cursor: "pointer",
							opacity: !loading && !input.trim() ? 0.5 : 1,
							flexShrink: 0,
						}}
					>
						{loading ? "■" : "↑"}
					</button>
				</div>
			</div>

			{/* API Key Dialog */}
			{showApiKeyDialog && (
				<div
					style={{
						position: "fixed",
						top: 0,
						left: 0,
						right: 0,
						bottom: 0,
						backgroundColor: "rgba(0, 0, 0, 0.7)",
						display: "flex",
						alignItems: "center",
						justifyContent: "center",
						zIndex: 1000,
					}}
				>
					<div
						style={{
							backgroundColor: "#2f2f2f",
							padding: "32px",
							borderRadius: "12px",
							maxWidth: "500px",
							width: "90%",
							border: "1px solid #444",
						}}
					>
						<h2 style={{ marginTop: 0, color: "#ececec" }}>
							Enter Anthropic API Key
						</h2>
						<p
							style={{ color: "#aaa", fontSize: "0.9em", marginBottom: "20px" }}
						>
							To use Claude models, please enter your Anthropic API key. Your
							key will be stored securely in your system keychain.
						</p>
						<input
							type="password"
							value={apiKeyInput}
							onChange={(e) => setApiKeyInput(e.target.value)}
							onKeyDown={(e) => e.key === "Enter" && handleSaveApiKey()}
							placeholder="sk-ant-..."
							style={{
								width: "100%",
								padding: "12px",
								borderRadius: "8px",
								border: "1px solid #555",
								backgroundColor: "#1a1a1a",
								color: "#ececec",
								fontSize: "1em",
								marginBottom: "20px",
								outline: "none",
							}}
						/>
						<div
							style={{
								display: "flex",
								gap: "12px",
								justifyContent: "flex-end",
							}}
						>
							<button
								type="button"
								onClick={() => {
									setShowApiKeyDialog(false);
									setApiKeyInput("");
								}}
								style={{
									padding: "10px 20px",
									borderRadius: "8px",
									border: "1px solid #555",
									backgroundColor: "transparent",
									color: "#aaa",
									cursor: "pointer",
									fontSize: "0.9em",
								}}
							>
								Cancel
							</button>
							<button
								type="button"
								onClick={handleSaveApiKey}
								disabled={!apiKeyInput.trim()}
								style={{
									padding: "10px 20px",
									borderRadius: "8px",
									border: "none",
									backgroundColor: apiKeyInput.trim() ? "#ececec" : "#555",
									color: apiKeyInput.trim() ? "#000" : "#888",
									cursor: apiKeyInput.trim() ? "pointer" : "not-allowed",
									fontSize: "0.9em",
								}}
							>
								Save Key
							</button>
						</div>
					</div>
				</div>
			)}
		</div>
	);
}