import 'dart:convert';

import 'package:http/http.dart' as http;

class StockPricePoint {
  final DateTime date;
  final double close;

  const StockPricePoint({required this.date, required this.close});
}

class StockPriceService {
  Future<List<StockPricePoint>> fetchPriceHistory(
    String ticker, {
    String range = '1mo',
    String interval = '1d',
  }) async {
    final normalizedTicker = ticker.trim().toUpperCase();
    final uri = Uri.parse(
      'https://query1.finance.yahoo.com/v8/finance/chart/$normalizedTicker?interval=$interval&range=$range',
    );

    final response = await http.get(uri, headers: {
      'User-Agent': 'Mozilla/5.0',
      'Accept': 'application/json',
    });

    if (response.statusCode != 200) {
      throw Exception('Failed to fetch price history for $normalizedTicker: ${response.statusCode}');
    }

    final json = jsonDecode(response.body) as Map<String, dynamic>;
    final chart = json['chart'] as Map<String, dynamic>?;
    final results = chart?['result'] as List?;

    if (results == null || results.isEmpty) {
      throw Exception('No price history returned for $normalizedTicker');
    }

    final result = results.first as Map<String, dynamic>;
    final timestamps = (result['timestamp'] as List?) ?? const [];
    final indicators = result['indicators'] as Map<String, dynamic>?;
    final adjCloseSeries = ((indicators?['adjclose'] as List?) ?? const [])
        .cast<Map<String, dynamic>?>();
    final quoteSeries = ((indicators?['quote'] as List?) ?? const [])
        .cast<Map<String, dynamic>?>();

    final adjCloseEntry = adjCloseSeries.isNotEmpty ? adjCloseSeries.first : null;
    final quoteEntry = quoteSeries.isNotEmpty ? quoteSeries.first : null;
    final adjCloseValues = adjCloseEntry == null ? null : adjCloseEntry['adjclose'];
    final quoteCloseValues = quoteEntry == null ? null : quoteEntry['close'];
    final closes = (adjCloseValues as List?) ?? (quoteCloseValues as List?) ?? const [];

    final points = <StockPricePoint>[];
    final itemCount = timestamps.length < closes.length ? timestamps.length : closes.length;

    for (int i = 0; i < itemCount; i++) {
      final timestamp = timestamps[i];
      final close = closes[i];

      if (timestamp is! num || close is! num) {
        continue;
      }

      points.add(
        StockPricePoint(
          date: DateTime.fromMillisecondsSinceEpoch(
            timestamp.toInt() * 1000,
            isUtc: true,
          ).toLocal(),
          close: close.toDouble(),
        ),
      );
    }

    if (points.isEmpty) {
      throw Exception('No valid price points returned for $normalizedTicker');
    }

    return points;
  }
}