using System.Net.Http;
using System.Net.Http.Json;
using System.Text.Json;
using ytLive.Models;
using AppLog = ytLive.Helpers.AppLog;

namespace ytLive.Services;
/// <summary>
/// Manages YouTube live stream lifecycle — create broadcasts,
/// bind stream keys, monitor health.
/// </summary>
public class YouTubeStreamService
{
    private readonly YouTubeAuthService _auth;
    private readonly HttpClient _http;
    private const string ApiBase = "https://www.googleapis.com/youtube/v3";

    public YouTubeStreamService(YouTubeAuthService auth, HttpClient? http = null)
    {
        _auth = auth;
        _http = http ?? new HttpClient();
    }

    private async Task<bool> EnsureToken()
    {
        if (_auth.CurrentChannel == null) return false;
        if (_auth.CurrentChannel.TokenExpiry <= DateTime.UtcNow.AddMinutes(5))
            return await _auth.RefreshToken();
        return true;
    }

    public async Task<string?> CreateBroadcast(string title, string description, DateTime scheduledStartTime, string? streamId = null)
    {
        if (!await EnsureToken()) return null;

        var broadcast = new
        {
            snippet = new
            {
                title,
                description,
                scheduledStartTime = scheduledStartTime.ToString("o"),
                categoryId = "22"  // People & Blogs
            },
            status = new
            {
                // Private-only by enforcement (ship step 7) — the Go Live dialog
                // is locked to Private and the service refuses anything else.
                privacyStatus = "private",
                selfDeclaredMadeForKids = false
            },
            // One-click go-live (TASK 5 design decision 1): auto start/stop with
            // no monitor stream and low latency. A reusable stream, when given,
            // binds here (boundStreamId) so no second bind round-trip is needed.
            contentDetails = BuildContentDetails(streamId)
        };

        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
        var response = await _http.PostAsJsonAsync(
            $"{ApiBase}/liveBroadcasts?part=snippet,status,contentDetails", broadcast);

        if (!response.IsSuccessStatusCode) return null;

        var json = await response.Content.ReadAsStringAsync();
        var data = JsonSerializer.Deserialize<JsonElement>(json);
        return data.GetProperty("id").GetString();
    }

    private static Dictionary<string, object?> BuildContentDetails(string? streamId)
    {
        var details = new Dictionary<string, object?>
        {
            ["enableAutoStart"] = true,
            ["enableAutoStop"] = true,
            ["enableMonitorStream"] = false,
            ["latencyPreference"] = "low",
        };
        if (streamId != null) details["boundStreamId"] = streamId;
        return details;
    }

    /// <summary>
    /// Pushes the creator-editable broadcast fields to YouTube via
    /// liveBroadcasts.update (part=snippet,status). Valid any time, including
    /// while live. Returns null on success, otherwise a human-readable error.
    /// Note: liveBroadcasts.update REPLACES the snippet part, so scheduledStartTime
    /// is re-sent unchanged from the stored value — omitting it would clear the
    /// schedule server-side.
    /// </summary>
    public async Task<string?> UpdateBroadcast(string broadcastId, BroadcastMetadata meta)
    {
        if (!await EnsureToken()) return "not signed in";

        var tags = meta.TagsCsv
            .Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
            .ToList();

        var broadcast = new
        {
            id = broadcastId,
            snippet = new
            {
                title = meta.Title,
                description = meta.Description,
                tags = tags,
                // update replaces the whole snippet part; echo the original schedule
                scheduledStartTime = (meta.ScheduledStartTime ?? DateTime.UtcNow).ToString("o"),
                categoryId = "22"
            },
            status = new
            {
                privacyStatus = string.IsNullOrWhiteSpace(meta.Visibility) ? "private" : meta.Visibility.ToLowerInvariant(),
                selfDeclaredMadeForKids = meta.MadeForKids
            }
        };

        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
        var response = await _http.PutAsJsonAsync(
            $"{ApiBase}/liveBroadcasts?part=snippet,status", broadcast);

        if (response.IsSuccessStatusCode) return null;
        var body = await response.Content.ReadAsStringAsync();
        AppLog.Write($"Broadcast update failed ({(int)response.StatusCode}): {body}");
        return $"YouTube rejected the update ({(int)response.StatusCode})";
    }

    /// <summary>Proper close-out (TASK 9 design decision 6 — implemented 2026-09-01;
    /// until then we relied entirely on enableAutoStop, leaving viewers on a frozen
    /// "stream offline" screen for ~a minute): POST liveBroadcasts.transition
    /// broadcastStatus=complete. MUST be called AFTER the encoder closed the RTMP
    /// push so no frames post-date the end. A broadcast YouTube already auto-completed
    /// answers 403 invalidTransition / 410 — logged and surfaced as an error string,
    /// never thrown: the stop path must not fail over a cosmetic close-out.</summary>
    public async Task<string?> EndBroadcastAsync(string broadcastId)
    {
        if (!await EnsureToken()) return "not signed in";

        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
        var response = await _http.PostAsync(
            $"{ApiBase}/liveBroadcasts/transition?broadcastStatus=complete&id={Uri.EscapeDataString(broadcastId)}&part=status",
            content: null);

        if (response.IsSuccessStatusCode) return null;
        var body = await response.Content.ReadAsStringAsync();
        AppLog.Write($"Broadcast transition(complete) failed ({(int)response.StatusCode}): {body}");
        return $"YouTube rejected the end transition ({(int)response.StatusCode})";
    }

    /// <summary>Returns the channel's reusable stream (TASK 5 design decision 2):
    /// lists existing streams first and reuses the one with cdn.isReusable=true,
    /// creating it with variable resolution/frame rate on first use. Binding to a
    /// broadcast happens at broadcast insert (boundStreamId), so one reusable
    /// stream serves every broadcast without recreation.</summary>
    public async Task<ReusableStream?> GetOrCreateReusableStreamAsync()
    {
        if (!await EnsureToken()) return null;

        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
        var listResponse = await _http.GetAsync(
            $"{ApiBase}/liveStreams?mine=true&part=snippet,cdn,status");
        if (!listResponse.IsSuccessStatusCode) return null;

        var listJson = JsonSerializer.Deserialize<JsonElement>(
            await listResponse.Content.ReadAsStringAsync());
        if (listJson.TryGetProperty("items", out var items))
        {
            foreach (var item in items.EnumerateArray())
            {
                if (item.TryGetProperty("cdn", out var cdn) &&
                    cdn.TryGetProperty("isReusable", out var reusable) &&
                    reusable.GetBoolean())
                {
                    var parsed = ParseStream(item);
                    if (parsed != null) return parsed;
                }
            }
        }

        var stream = new
        {
            snippet = new { title = "LlamaCasty Reusable Stream" },
            cdn = new
            {
                ingestionType = "rtmp",
                resolution = "variable",
                frameRate = "variable",
                isReusable = true
            }
        };
        var response = await _http.PostAsJsonAsync(
            $"{ApiBase}/liveStreams?part=snippet,cdn", stream);
        if (!response.IsSuccessStatusCode) return null;

        var json = JsonSerializer.Deserialize<JsonElement>(await response.Content.ReadAsStringAsync());
        return ParseStream(json);
    }

    private static ReusableStream? ParseStream(JsonElement item)
    {
        if (!item.TryGetProperty("id", out var id) ||
            !item.TryGetProperty("cdn", out var cdn) ||
            !cdn.TryGetProperty("ingestionInfo", out var info))
        {
            return null;
        }

        var streamId = id.GetString();
        var address = info.TryGetProperty("ingestionAddress", out var addr) ? addr.GetString() : null;
        var name = info.TryGetProperty("streamName", out var nameEl) ? nameEl.GetString() : null;
        if (string.IsNullOrWhiteSpace(streamId) || string.IsNullOrWhiteSpace(address) || string.IsNullOrWhiteSpace(name))
            return null;

        return new ReusableStream(streamId, address, name);
    }

    /// <summary>Polls the reusable stream's health (TASK 5 item 3) via
    /// liveStreams.status — report-by-exception: good/ok/noData yield an empty
    /// issue list, warning/error entries in configurationIssues[] drive the
    /// banner. Null on failure or an empty response, never a throw.</summary>
    public async Task<StreamHealth?> GetStreamHealthAsync(string streamId)
    {
        if (!await EnsureToken()) return null;

        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
        var response = await _http.GetAsync(
            $"{ApiBase}/liveStreams?part=status&id={streamId}");
        if (!response.IsSuccessStatusCode) return null;

        var json = JsonSerializer.Deserialize<JsonElement>(await response.Content.ReadAsStringAsync());
        var items = json.GetProperty("items");
        if (items.GetArrayLength() == 0) return null;

        var status = items[0].GetProperty("status");
        var health = new StreamHealth
        {
            HealthStatus = status.TryGetProperty("healthStatus", out var healthStatus)
                ? healthStatus.GetString()
                : null,
        };
        if (status.TryGetProperty("configurationIssues", out var issues))
        {
            foreach (var issue in issues.EnumerateArray())
            {
                var severity = issue.TryGetProperty("severity", out var sev) ? sev.GetString() : null;
                var type = issue.TryGetProperty("type", out var t) ? t.GetString() : null;
                health.ConfigurationIssues.Add(new StreamConfigurationIssue
                {
                    Severity = severity switch
                    {
                        "error" => StreamIssueSeverity.Error,
                        "warning" => StreamIssueSeverity.Warning,
                        _ => StreamIssueSeverity.Info,
                    },
                    Type = type,
                });
            }
        }
        return health;
    }

    /// <summary>TASK 41 — mock chat input: posts a real text message into the live
    /// chat via <c>liveChat/messages.insert</c>. Requires the same OAuth scopes the
    /// app already holds (youtube.force-ssl). Returns itself or a human-readable
    /// error; never throws. The inserted message round-trips back through the normal
    /// chat poll (~2s) and renders through the live overlay path.</summary>
    public async Task<string?> InsertChatMessageAsync(string liveChatId, string messageText)
    {
        if (!await EnsureToken()) return "not signed in";

        var body = new
        {
            snippet = new
            {
                liveChatId,
                textMessageDetails = new { messageText }
            }
        };

        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
        var response = await _http.PostAsJsonAsync(
            $"{ApiBase}/liveChat/messages?part=snippet", body);

        if (response.IsSuccessStatusCode)
        {
            AppLog.Write($"Test chat message inserted into {liveChatId}");
            return null;
        }

        var errorBody = await response.Content.ReadAsStringAsync();
        AppLog.Write($"Chat message insert failed ({(int)response.StatusCode}): {errorBody}");
        return $"YouTube rejected the message ({(int)response.StatusCode})";
    }

    /// <summary>Returns the liveChatId for a broadcast by fetching its contentDetails.
    /// The liveChatId is needed to poll chat messages. Called after broadcast creation
    /// in PrepareAndStartLiveAsync.</summary>
    public async Task<string?> GetBroadcastLiveChatIdAsync(string broadcastId)
    {
        if (!await EnsureToken()) return null;

        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
        var response = await _http.GetAsync(
            $"{ApiBase}/liveBroadcasts?part=contentDetails&id={broadcastId}");
        if (!response.IsSuccessStatusCode) return null;

        var json = await response.Content.ReadAsStringAsync();
        var data = JsonSerializer.Deserialize<JsonElement>(json);
        var items = data.GetProperty("items");
        if (items.GetArrayLength() == 0) return null;

        var contentDetails = items[0].GetProperty("contentDetails");
        if (contentDetails.TryGetProperty("liveChatId", out var liveChatId))
            return liveChatId.GetString();

        return null;
    }
}