/**
 * webSearchLogger.ts
 * Centralized structured logger for the web search pipeline on the client side.
 * Outputs consistently formatted, emoji-tagged logs to the React Native / Metro console.
 */

type LogLevel = 'INFO' | 'WARN' | 'ERROR' | 'DEBUG';

const ICONS: Record<LogLevel, string> = {
    INFO: 'ℹ️ ',
    WARN: '⚠️ ',
    ERROR: '❌',
    DEBUG: '🔍',
};

function formatMeta(meta?: Record<string, any>): string {
    if (!meta) return '';
    try {
        return '\n  ' + JSON.stringify(meta, null, 2).replace(/\n/g, '\n  ');
    } catch {
        return '';
    }
}

function log(level: LogLevel, phase: string, message: string, meta?: Record<string, any>) {
    const ts = new Date().toISOString();
    const metaStr = formatMeta(meta);
    const prefix = `[${ts}] ${ICONS[level]} [WebSearch/${phase}]`;
    const fullMsg = `${prefix} ${message}${metaStr}`;

    switch (level) {
        case 'ERROR':
            console.error(fullMsg);
            break;
        case 'WARN':
            console.warn(fullMsg);
            break;
        default:
            console.log(fullMsg);
    }
}

function logSection(title: string) {
    const border = '─'.repeat(55);
    console.log(`\n${border}`);
    console.log(`  ${title}`);
    console.log(`${border}`);
}

/** Rough tokens estimate (~4 chars per token) */
function estimateTokens(text: string): number {
    return Math.ceil(text.length / 4);
}

// ─── Public API ────────────────────────────────────────────────────────────────

export const WebSearchLogger = {
    pipelineStart(query: string, searchEndpoint: string) {
        logSection(`🚀 Web Search Pipeline Started`);
        log('INFO', 'Init', `New search initiated`, {
            query,
            searchEndpoint,
            timestamp: new Date().toISOString(),
        });
    },

    endpointResolved(host: string, port: number, searchEndpoint: string) {
        log('INFO', 'Endpoint', `Search service URL resolved`, {
            lmStudioHost: host,
            lmStudioPort: port,
            searchServiceEndpoint: searchEndpoint,
        });
    },

    requestSent(query: string, maxContextLength: number, timeoutMs = 30000) {
        log('INFO', 'Request', `Sending search request to local service`, {
            query,
            maxContextLength,
            estimatedTokenBudget: estimateTokens('x'.repeat(maxContextLength)),
            timeoutMs,
        });
    },

    requestFailed(status: number, statusText: string) {
        log('ERROR', 'Request', `Search service returned error`, {
            httpStatus: status,
            statusText,
        });
    },

    serviceUnreachable(error: unknown, isTimeout = false) {
        const err = error instanceof Error ? error : new Error(String(error));
        const isConnectionRefused =
            err.message.includes('Network request failed') ||
            err.message.includes('ECONNREFUSED') ||
            err.message.includes('Connection refused');

        const message = isTimeout
            ? `Search service timeout (30s) — service may be overloaded or unreachable`
            : isConnectionRefused
            ? `Search service is NOT running — connection refused`
            : `Cannot reach local search service`;

        log('ERROR', 'Request', message, {
            error: err.message,
            isTimeout,
            isConnectionRefused,
            diagnosis: isConnectionRefused
                ? 'The local-search-service Node.js process is not running on this machine'
                : isTimeout
                ? 'Service is running but not responding within 30s (SearXNG may be slow)'
                : 'Unknown network error',
            hint: 'Run: cd local-search-service && npx ts-node server.ts',
        });
    },

    contextReceived(
        context: string,
        sources: Array<{ title: string; url: string }>,
        meta?: {
            requestId?: string;
            totalLatencyMs?: number;
            finalContextChars?: number;
            finalContextEstimatedTokens?: number;
            sourcesKept?: number;
            sourcesDropped?: number;
            pruned?: boolean;
        },
    ) {
        logSection(`✅ Context Received from Search Service`);
        log('INFO', 'Context', `Web search context ready`, {
            contextChars: context.length,
            estimatedTokens: estimateTokens(context),
            sourcesReceived: sources.length,
            sourceTitles: sources.map((s) => s.title.substring(0, 60)),
            sourceUrls: sources.map((s) => s.url),
            ...(meta ?? {}),
        });
    },

    contextAnalysis(systemPromptChars: number, historyChars: number, searchContextChars: number) {
        logSection(`🧠 Context Window Analysis`);
        const totalChars = systemPromptChars + historyChars + searchContextChars;
        const totalTokens = estimateTokens('x'.repeat(totalChars));
        log('INFO', 'Analysis', `Total context before sending to LLM`, {
            systemPromptChars,
            systemPromptTokens: estimateTokens('x'.repeat(systemPromptChars)),
            chatHistoryChars: historyChars,
            chatHistoryTokens: estimateTokens('x'.repeat(historyChars)),
            searchContextChars,
            searchContextTokens: estimateTokens('x'.repeat(searchContextChars)),
            totalChars,
            estimatedTotalTokens: totalTokens,
            note: 'Token estimates are approximate (~4 chars/token). Actual tokenization varies by model.',
        });
    },

    llmRequestStart(model: string, messageCount: number) {
        logSection(`🤖 LLM Request`);
        log('INFO', 'LLM', `Sending messages to LM Studio`, {
            model,
            totalMessages: messageCount,
            streamingEnabled: true,
        });
    },

    llmStreamComplete(assistantMessageId: string, chunkCount?: number) {
        log('INFO', 'LLM', `Stream complete — response generated`, {
            assistantMessageId,
            ...(chunkCount !== undefined ? { chunkCount } : {}),
        });
    },

    llmError(error: Error) {
        log('ERROR', 'LLM', `LLM stream error`, {
            error: error.message,
            stack: error.stack?.split('\n').slice(0, 3).join(' | '),
        });
    },

    pipelineComplete(query: string, totalLatencyMs: number, withSearch: boolean) {
        logSection(`🏁 Pipeline Complete`);
        log('INFO', 'Done', `Full request cycle finished`, {
            query,
            totalLatencyMs,
            webSearchUsed: withSearch,
        });
        console.log('─'.repeat(55) + '\n');
    },
};