DorkNet/DorkNet.Server/Controllers/API/Relationships/V2/RelationshipsController.cs

using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using DorkNet.Server.Auth;
using DorkNet.Server.Data;
using DorkNet.Server.Data.Entities;
using DorkNet.Server.Services;

// Storage-side enum aliased so the wire mapping stays explicit at
// every callsite. Wire enum values (RelationshipType /
// ReciprocalStatus) live in this file as constants — they're tied
// to the disassembly and not used elsewhere.
using EntityStatus = DorkNet.Server.Data.Entities.RelationshipStatus;

namespace DorkNet.Server.Controllers.API.Relationships.V2;

/// <summary>
/// api/relationships/v2 — friendship + reciprocal-state endpoints.
///
/// All routes / wire shapes verified against the patched 2020 client:
///   Cpp2IL_ISIL/IsilDump/Assembly-CSharp/RecNet/Relationships.txt
///   Cpp2IL_ISIL/IsilDump/Assembly-CSharp/RecNet/Relationship.txt
///
/// Wire response = a Relationship object (or List of them for /get).
/// Relationship.Deserialize strict-reads via Util.GetKey&lt;T&gt;:
///   "PlayerID"          (int) — REQUIRED — the OTHER account's id
///   "RelationshipType"  (int) — REQUIRED — 0..3
///   "Muted"             (int) — REQUIRED — ReciprocalStatus 0..3
///   "Ignored"           (int) — REQUIRED — ReciprocalStatus 0..3
///   "Favorited"         (int) — optional (Util.GetKeyOrDefault, defaults 0)
///
/// RelationshipType (from caller's perspective):
///   0 None, 1 FriendRequestSent, 2 FriendRequestReceived, 3 Friend
/// ReciprocalStatus (symmetric flag — who set it):
///   0 None, 1 Local (just me), 2 Remote (just them), 3 Mutual
///
/// URLs called from the watch (Relationships.txt, all under
/// "api/relationships/"):
///   POST v2/addfriend?id={N}            AddFriend
///   POST v2/removefriend?id={N}         RemoveFriend / cancel-pending
///   POST v2/sendfriendrequest?id={N}    SendFriendRequest
///   POST v2/acceptfriendrequest?id={N}  AcceptFriendRequest
///   POST v1/favorite?id={N}             FavoritePlayer
///   POST v1/unfavorite?id={N}           UnfavoritePlayer
///   POST v1/mute / unmute / ignore / unignore (PostPreferenceChange)
///   GET  v2/get                         GetMyRelationships
/// All POST URLs return one Relationship; GET returns List&lt;Relationship&gt;.
/// </summary>
[ApiController]
[Authorize]
public class RelationshipsController(
    DorkNetDbContext db,
    NotificationService notifications,
    SystemNotificationService systemNotifications,
    ServerSettingsService settings) : ControllerBase
{
    // RelationshipType — int values match Relationship.RelationshipType
    // in the patched dump.cs.
    private const int RT_None                  = 0;
    private const int RT_FriendRequestSent     = 1;
    private const int RT_FriendRequestReceived = 2;
    private const int RT_Friend                = 3;

    // ReciprocalStatus values — also match the dump.cs enum.
    private const int RS_None   = 0;
    private const int RS_Local  = 1;
    private const int RS_Remote = 2;
    private const int RS_Mutual = 3;

    private long CurrentPlayerId => this.RequireCurrentPlayerId();

    // ── GET /api/relationships/v2/get ────────────────────────────────
    // Watch URL: "api/relationships/v2/get". Returns the caller's full
    // relationship list as List<Relationship>.
    [HttpGet("api/relationships/v2/get")]
    public async Task<ActionResult> GetMyRelationships()
    {
        var me = CurrentPlayerId;

        // Global-friends mode (admin toggle): synthesize a Friend row for
        // every other account WITHOUT persisting anything. Real rows are
        // overlaid so mute/favorite still apply and Blocked stays non-friend.
        if (await settings.IsGlobalFriendsEnabledAsync())
            return Ok(await BuildGlobalFriendListAsync(me));

        var rels = await db.Relationships
            .Where(r => r.RequesterId == me || r.TargetId == me)
            .ToListAsync();
        // Merge the (up to two) rows per pair so a favorite/mute/ignore the
        // caller set on a friendship the OTHER player initiated isn't dropped
        // by the watch (which keys its list by PlayerID — duplicate ids lose).
        var wire = rels
            .GroupBy(r => r.RequesterId == me ? r.TargetId : r.RequesterId)
            .Select(g => BuildMerged(me, g.Key, g.ToList()))
            .ToList();
        return Ok(wire);
    }

    /// <summary>Synthesize the caller's friend list as "everyone" for the
    /// global-friends toggle. One Friend entry per other account; real rows
    /// are overlaid so a Block stays None and mute/favorite carry through.</summary>
    private async Task<List<Dictionary<string, object>>> BuildGlobalFriendListAsync(long me)
    {
        var realRows = await db.Relationships
            .Where(r => r.RequesterId == me || r.TargetId == me)
            .ToListAsync();
        // Group both directional rows per pair so the caller's favorite/mute/
        // ignore (stored on the row where they're the requester) survives even
        // when the friendship row itself was created by the other player.
        var realByOther = realRows
            .GroupBy(r => r.RequesterId == me ? r.TargetId : r.RequesterId)
            .ToDictionary(g => g.Key, g => g.ToList());

        var others = await db.Players
            .Where(p => p.Id != me && p.Id != RelationshipQueries.SystemAccountId)
            .Select(p => new { p.Id, p.Username })
            .ToListAsync();

        var wire = new List<Dictionary<string, object>>(others.Count);
        foreach (var other in others)
        {
            var otherId = other.Id;
            if (realByOther.TryGetValue(otherId, out var pair))
            {
                // A real block wins — that pair is genuinely not friends.
                if (pair.Any(r => r.Status == EntityStatus.Blocked)) { wire.Add(EmptyRelationship(otherId)); continue; }
                // Carry the caller's own preference bits from their row.
                var mineRow = pair.FirstOrDefault(r => r.RequesterId == me);
                wire.Add(SynthFriend(otherId, mineRow, me));
            }
            else
            {
                // Hide auto-generated Player_NNN placeholders from the
                // synthesized list (they never set a real username).
                if (RelationshipQueries.IsPlaceholderUsername(other.Username)) continue;
                wire.Add(SynthFriend(otherId, null, me));
            }
        }
        return wire;
    }

    /// <summary>A synthetic Friend relationship for global-friends mode,
    /// carrying mute/ignore/favorite from the caller's real row when present.</summary>
    private static Dictionary<string, object> SynthFriend(long other, RelationshipEntity? real, long me)
    {
        var mineDir = real is not null && real.RequesterId == me;
        return new()
        {
            ["PlayerID"]         = (int)other,
            ["RelationshipType"] = RT_Friend,
            ["Muted"]            = mineDir && real!.Muted     ? 1 : 0,
            ["Ignored"]          = mineDir && real!.Ignored   ? 1 : 0,
            ["Favorited"]        = mineDir && real!.Favorited ? 1 : 0,
        };
    }

    /// <summary>GET <c>api/relationships/v2/personaldetails/{playerId}</c>
    /// — single relationship row from the caller's perspective. Used
    /// by the watch's profile-card view to determine whether to show
    /// the "Add Friend" or "Remove Friend" affordance. Returns the
    /// same Relationship wire shape as <c>v2/get</c>'s list elements.</summary>
    [HttpGet("api/relationships/v2/personaldetails/{playerId:long}")]
    public async Task<ActionResult> PersonalDetails(long playerId)
    {
        var me = CurrentPlayerId;
        if (playerId <= 0 || playerId == me) return Ok(EmptyRelationship(playerId));
        var pair = await db.Relationships
            .Where(r => (r.RequesterId == me && r.TargetId == playerId) ||
                        (r.RequesterId == playerId && r.TargetId == me))
            .ToListAsync();
        var blocked = pair.Any(r => r.Status == EntityStatus.Blocked);
        var mineRow = pair.FirstOrDefault(r => r.RequesterId == me);

        // Global-friends mode: report Friend for any real account that isn't
        // the system account and isn't explicitly blocked. Placeholder
        // Player_NNN accounts are hidden unless there's a genuine row.
        if (playerId != RelationshipQueries.SystemAccountId
            && !blocked
            && await settings.IsGlobalFriendsEnabledAsync())
        {
            var isPlaceholder = pair.Count == 0 && RelationshipQueries.IsPlaceholderUsername(
                await db.Players.Where(p => p.Id == playerId)
                    .Select(p => p.Username).FirstOrDefaultAsync());
            if (!isPlaceholder) return Ok(SynthFriend(playerId, mineRow, me));
        }

        return Ok(pair.Count == 0 ? EmptyRelationship(playerId) : BuildMerged(me, playerId, pair));
    }

    // ── /api/relationships/v2/sendfriendrequest?id={N} ───────────────
    // Watch URL from Relationships.txt: "{0}v2/sendfriendrequest?id={1}".
    // The ISIL labels the call site Core.Post but the live trace shows
    // the watch sending GET — accepting both is harmless and the
    // safest cross-build choice.
    [HttpGet("api/relationships/v2/sendfriendrequest")]
    [HttpPost("api/relationships/v2/sendfriendrequest")]
    public async Task<ActionResult> SendFriendRequest([FromQuery] long id)
    {
        var me = CurrentPlayerId;
        if (id <= 0 || id == me)
            return Ok(EmptyRelationship(id));

        var pair = await db.Relationships
            .Where(r => (r.RequesterId == me && r.TargetId == id) ||
                        (r.RequesterId == id && r.TargetId == me))
            .ToListAsync();

        // Anything that already defines a status (friend/pending/block) wins —
        // a None row is preference-only and doesn't count as a relationship.
        if (pair.Any(r => r.Status != EntityStatus.None))
            return Ok(BuildMerged(me, id, pair));

        // Promote the caller's own preference-only row if present (keeping its
        // favorite/mute/ignore bits) rather than spawning a second row.
        var row = pair.FirstOrDefault(r => r.RequesterId == me);
        if (row is not null)
        {
            row.Status    = EntityStatus.PendingSent;
            row.UpdatedAt = DateTime.UtcNow;
        }
        else
        {
            row = new RelationshipEntity
            {
                RequesterId = me,
                TargetId    = id,
                Status      = EntityStatus.PendingSent,
            };
            db.Relationships.Add(row);
        }
        await db.SaveChangesAsync();

        await PushPairAsync(me, id);
        // The "X sent you a friend request" row in the target's notifications.
        await systemNotifications.SendAsync(id, SystemNotificationService.MessageType.FriendInvite, fromPlayerId: me);
        return Ok(BuildRelationship(row, me));
    }

    // ── /api/relationships/v2/acceptfriendrequest?id={N} ────────────
    [HttpGet("api/relationships/v2/acceptfriendrequest")]
    [HttpPost("api/relationships/v2/acceptfriendrequest")]
    public async Task<ActionResult> AcceptFriendRequest([FromQuery] long id)
    {
        var me = CurrentPlayerId;
        if (id <= 0)
            return Ok(EmptyRelationship(id));

        // Only an incoming pending row can be accepted. The other side
        // must have requested us — RequesterId=them, TargetId=me.
        var rel = await db.Relationships.FirstOrDefaultAsync(r =>
            r.RequesterId == id && r.TargetId == me &&
            r.Status == EntityStatus.PendingSent);
        if (rel is null)
            return Ok(EmptyRelationship(id));

        rel.Status    = EntityStatus.Friend;
        rel.UpdatedAt = DateTime.UtcNow;
        await db.SaveChangesAsync();

        await PushPairAsync(me, id);
        await systemNotifications.SendAsync(id, SystemNotificationService.MessageType.FriendRequestAccepted, fromPlayerId: me);
        return Ok(BuildRelationship(rel, me));
    }

    // ── /api/relationships/v2/removefriend?id={N} ────────────────────
    // Symmetrical: undoes a friendship OR cancels a pending request OR
    // declines an incoming one. Block rows are left alone — the watch
    // has a separate explicit unblock path. Live trace shows the watch
    // sending GET (BestHTTP queueing oddity vs the ISIL Core.Post call);
    // accept both verbs.
    [HttpGet("api/relationships/v2/removefriend")]
    [HttpPost("api/relationships/v2/removefriend")]
    public async Task<ActionResult> RemoveFriend([FromQuery] long id)
    {
        var me = CurrentPlayerId;
        if (id <= 0)
            return Ok(EmptyRelationship(id));

        var pair = await db.Relationships
            .Where(r => (r.RequesterId == me && r.TargetId == id) ||
                        (r.RequesterId == id && r.TargetId == me))
            .ToListAsync();
        if (pair.Count == 0)
            return Ok(EmptyRelationship(id));

        // Drop every non-block row for the pair (friendship row + any stray
        // preference row), leaving a block intact — the watch unblocks
        // through a separate path.
        var removable = pair.Where(r => r.Status != EntityStatus.Blocked).ToList();
        if (removable.Count == 0)
            return Ok(BuildMerged(me, id, pair));

        db.Relationships.RemoveRange(removable);
        await db.SaveChangesAsync();
        await PushPairAsync(me, id);

        var remaining = pair.Except(removable).ToList();
        return Ok(remaining.Count == 0 ? EmptyRelationship(id) : BuildMerged(me, id, remaining));
    }

    // ── /api/relationships/v2/addfriend?id={N} ───────────────────────
    // Per the disassembly, AddFriend is its own endpoint distinct from
    // SendFriendRequest. Live trace shows the watch sending GET; ISIL
    // says Core.Post. Accept both verbs.
    [HttpGet("api/relationships/v2/addfriend")]
    [HttpPost("api/relationships/v2/addfriend")]
    public async Task<ActionResult> AddFriend([FromQuery] long id)
    {
        var me = CurrentPlayerId;
        if (id <= 0 || id == me)
            return Ok(EmptyRelationship(id));

        var pair = await db.Relationships
            .Where(r => (r.RequesterId == me && r.TargetId == id) ||
                        (r.RequesterId == id && r.TargetId == me))
            .ToListAsync();

        // Don't override a block, and don't spawn a duplicate when a
        // friendship row already exists (in either direction).
        if (pair.Any(r => r.Status == EntityStatus.Blocked) ||
            pair.Any(r => r.Status == EntityStatus.Friend))
            return Ok(BuildMerged(me, id, pair));

        // Promote the caller's own row (preference-only or pending) to Friend,
        // or create one if none exists.
        var existing = pair.FirstOrDefault(r => r.RequesterId == me);
        if (existing is null)
        {
            existing = new RelationshipEntity
            {
                RequesterId = me,
                TargetId    = id,
                Status      = EntityStatus.Friend,
            };
            db.Relationships.Add(existing);
        }
        else
        {
            existing.Status    = EntityStatus.Friend;
            existing.UpdatedAt = DateTime.UtcNow;
        }
        await db.SaveChangesAsync();
        await PushPairAsync(me, id);
        await systemNotifications.SendAsync(id, SystemNotificationService.MessageType.FriendRequestAccepted, fromPlayerId: me);
        return Ok(BuildRelationship(existing, me));
    }

    // ── v1 favorite / unfavorite ─────────────────────────────────────
    // Watch URLs: "api/relationships/v1/favorite?id={N}" and
    // "api/relationships/v1/unfavorite?id={N}". These return a
    // boolean-ish RecNetResult per the FavoritePlayer/UnfavoritePlayer
    // disassembly, not a Relationship. The flag is persisted on the caller's
    // directional row and surfaced back through v2/get + personaldetails
    // (see BuildMerged).
    //
    // VERB: the 2020 watch sends these as GET (RecNet.Relationships
    // FavoritePlayer/UnfavoritePlayer/etc. call Core.Get — verified in the
    // readable March dump at Relationships.txt:1675/1834, and the December
    // build hits the same obfuscated Core-GET wrapper). The endpoints were
    // POST-only, so the watch's GET returned HTTP 405 ("Error favoriting
    // player: HTTP Error 405"). Accept GET (real verb) + POST (cross-build
    // safety), mirroring the friend endpoints above.
    [HttpGet("api/relationships/v1/favorite")]
    [HttpPost("api/relationships/v1/favorite")]
    public Task<IActionResult> Favorite([FromQuery] long id) => SetPreference(id, favorited: true);

    [HttpGet("api/relationships/v1/unfavorite")]
    [HttpPost("api/relationships/v1/unfavorite")]
    public Task<IActionResult> Unfavorite([FromQuery] long id) => SetPreference(id, favorited: false);

    [HttpGet("api/relationships/v1/mute")]
    [HttpPost("api/relationships/v1/mute")]
    public Task<IActionResult> Mute([FromQuery] long id, [FromForm(Name = "PlayerId")] long? formId)
        => SetPreference(id != 0 ? id : formId ?? 0, muted: true);

    [HttpGet("api/relationships/v1/unmute")]
    [HttpPost("api/relationships/v1/unmute")]
    public Task<IActionResult> Unmute([FromQuery] long id, [FromForm(Name = "PlayerId")] long? formId)
        => SetPreference(id != 0 ? id : formId ?? 0, muted: false);

    [HttpGet("api/relationships/v1/ignore")]
    [HttpPost("api/relationships/v1/ignore")]
    public Task<IActionResult> Ignore([FromQuery] long id, [FromForm(Name = "PlayerId")] long? formId)
        => SetPreference(id != 0 ? id : formId ?? 0, ignored: true);

    [HttpGet("api/relationships/v1/unignore")]
    [HttpPost("api/relationships/v1/unignore")]
    public Task<IActionResult> Unignore([FromQuery] long id, [FromForm(Name = "PlayerId")] long? formId)
        => SetPreference(id != 0 ? id : formId ?? 0, ignored: false);

    /// <summary>Update favorited/muted/ignored on the caller's row.
    /// Creates a placeholder row when none exists (so an "ignore"
    /// before any friend request is still recorded).</summary>
    private async Task<IActionResult> SetPreference(long otherId,
        bool? favorited = null, bool? muted = null, bool? ignored = null)
    {
        var me = this.RequireCurrentPlayerId();
        if (otherId <= 0 || otherId == me)
            return Ok(new Models.Auth.RecNetResult { Success = false, Error = "invalid_id" });

        var row = await db.Relationships.FirstOrDefaultAsync(r =>
            r.RequesterId == me && r.TargetId == otherId);
        if (row is null)
        {
            // A preference (favorite/mute/ignore) is the caller's own bit and
            // lives on their own directional row. Status None — favorite/mute/
            // ignore must NOT fabricate a friendship; the real friendship row
            // (this direction or the other) carries the actual status and the
            // read path merges the two.
            row = new RelationshipEntity
            {
                RequesterId = me,
                TargetId = otherId,
                Status = EntityStatus.None,
            };
            db.Relationships.Add(row);
        }
        if (favorited is bool f) row.Favorited = f;
        if (muted is bool m) row.Muted = m;
        if (ignored is bool i) row.Ignored = i;
        row.UpdatedAt = DateTime.UtcNow;
        await db.SaveChangesAsync();
        // The HTTP reply is only an ack; the updated row reaches the client
        // through RelationshipChanged. A preference is the caller's own bit,
        // so only the caller is told.
        await PushPairAsync(me, otherId, notifyOther: false);
        return Ok(new Models.Auth.RecNetResult { Success = true, Error = string.Empty });
    }

    public sealed class BulkIgnoreRequest
    {
        public int Platform { get; set; }
        public List<string>? PlatformUserIds { get; set; }
    }

    /// <summary>POST <c>api/relationships/v1/bulkignoreplatformusers</c>
    /// — bulk-import Steam/Oculus blocks. Persists to
    /// <see cref="PlatformIgnoreEntity"/> so when those users sign
    /// up later we can auto-set their relationship to Ignored.</summary>
    [HttpPost("api/relationships/v1/bulkignoreplatformusers")]
    [Authorize]
    public async Task<IActionResult> BulkIgnorePlatformUsers([FromBody] BulkIgnoreRequest req)
    {
        var me = this.RequireCurrentPlayerId();
        if (req?.PlatformUserIds is null || req.PlatformUserIds.Count == 0)
            return Ok(new { Imported = 0 });

        var added = 0;
        foreach (var puid in req.PlatformUserIds.Distinct())
        {
            if (string.IsNullOrWhiteSpace(puid)) continue;
            var exists = await db.PlatformIgnores.AnyAsync(i =>
                i.PlayerId == me && i.Platform == req.Platform && i.PlatformUserId == puid);
            if (exists) continue;
            db.PlatformIgnores.Add(new PlatformIgnoreEntity
            {
                PlayerId = me,
                Platform = req.Platform,
                PlatformUserId = puid,
            });
            added++;
        }
        await db.SaveChangesAsync();
        return Ok(new { Imported = added });
    }

    [HttpGet("api/relationships/mutualfriends")]
    public async Task<IActionResult> MutualFriends([FromQuery] long playerId)
    {
        var me = CurrentPlayerId;
        if (playerId <= 0 || playerId == me) return Ok(Array.Empty<object>());
        var mine = await FriendIdsAsync(me);
        var theirs = await FriendIdsAsync(playerId);
        var mutualIds = mine.Intersect(theirs).Take(100).ToList();
        var players = await db.Players
            .Where(p => mutualIds.Contains(p.Id))
            .Select(p => new
            {
                AccountId = (int)p.Id,
                p.Username,
                p.DisplayName,
                ProfileImage = p.ProfileImageName ?? string.Empty,
            })
            .ToListAsync();
        return Ok(players);
    }

    [HttpPost("api/relationships/sendfriendintroductions")]
    public async Task<IActionResult> SendFriendIntroductions(
        [FromForm] long playerId,
        [FromForm] long introducedPlayerId)
    {
        var me = CurrentPlayerId;
        if (playerId <= 0 || introducedPlayerId <= 0)
            return BadRequest("missing_player");
        db.Messages.Add(new MessageEntity
        {
            SenderPlayerId = me,
            RecipientPlayerId = playerId,
            Type = 30,
            Body = $"Friend introduction:{introducedPlayerId}",
        });
        await db.SaveChangesAsync();
        return Ok(new { Success = true });
    }

    [HttpPost("api/relationships/v1/addfriendwithcode")]
    [HttpGet("api/relationships/v1/addfriendwithcode")]
    public async Task<ActionResult> AddFriendWithCode([FromQuery] string? code, [FromForm] string? formCode)
    {
        var raw = (code ?? formCode ?? string.Empty).Trim();
        if (raw.Length == 0) return Ok(EmptyRelationship(0));
        long? id = long.TryParse(raw, out var parsed) ? parsed : null;
        if (id is null)
        {
            id = await db.Players
                .Where(p => p.Username == raw)
                .Select(p => (long?)p.Id)
                .FirstOrDefaultAsync();
        }
        if (id is not long playerId) return Ok(EmptyRelationship(0));
        return await AddFriend(playerId);
    }

    // ── helpers ──────────────────────────────────────────────────────

    /// <summary>Push RelationshipChanged for the pair (<paramref name="me"/>,
    /// <paramref name="other"/>) after a change, each side getting its OWN view
    /// of the relationship. Without this a friend request, accept or unfriend
    /// only showed up after the friends list was refetched, and the client
    /// never re-subscribed to the new friend's presence.</summary>
    private async Task PushPairAsync(long me, long other, bool notifyOther = true)
    {
        var pair = await db.Relationships
            .Where(r => (r.RequesterId == me && r.TargetId == other) ||
                        (r.RequesterId == other && r.TargetId == me))
            .ToListAsync();
        var globalFriends = await settings.IsGlobalFriendsEnabledAsync();

        await notifications.RelationshipChanged(me, ViewOf(me, other, pair, globalFriends));
        if (notifyOther)
            await notifications.RelationshipChanged(other, ViewOf(other, me, pair, globalFriends));
    }

    /// <summary>The relationship from <paramref name="viewer"/>'s side, the way
    /// <c>v2/get</c> would list it.</summary>
    private static Dictionary<string, object> ViewOf(
        long viewer, long other, List<RelationshipEntity> pair, bool globalFriends)
    {
        if (globalFriends
            && other != RelationshipQueries.SystemAccountId
            && !pair.Any(r => r.Status == EntityStatus.Blocked))
            return SynthFriend(other, pair.FirstOrDefault(r => r.RequesterId == viewer), viewer);
        return pair.Count == 0 ? EmptyRelationship(other) : BuildMerged(viewer, other, pair);
    }

    private async Task<HashSet<long>> FriendIdsAsync(long playerId)
    {
        var rows = await db.Relationships
            .Where(r => r.Status == EntityStatus.Friend
                        && (r.RequesterId == playerId || r.TargetId == playerId))
            .Select(r => r.RequesterId == playerId ? r.TargetId : r.RequesterId)
            .ToListAsync();
        return rows.ToHashSet();
    }

    /// <summary>Map a storage row to the watch's wire RelationshipType
    /// from <paramref name="me"/>'s perspective. PendingSent flips
    /// direction depending on which side originated.</summary>
    private static int MapType(RelationshipEntity r, long me) => r.Status switch
    {
        EntityStatus.Friend            => RT_Friend,
        EntityStatus.Blocked           => RT_None, // Blocked is not a friendship; the watch reads block state via a separate flag we don't track yet.
        EntityStatus.PendingSent       => r.RequesterId == me ? RT_FriendRequestSent : RT_FriendRequestReceived,
        EntityStatus.PendingReceived   => r.RequesterId == me ? RT_FriendRequestReceived : RT_FriendRequestSent,
        _                              => RT_None,
    };

    /// <summary>
    /// Build the wire object the patched <c>Relationship.Deserialize</c>
    /// reads. Keys are case-sensitive (Util.GetKey is a Dictionary
    /// TryGetValue) — we ship exactly what's in the disassembly.
    /// Implemented as a Dictionary because System.Text.Json's
    /// case-insensitive collision check rejects anonymous types with
    /// PascalCase property names like "PlayerID" + "Muted" if any
    /// other property could collide on lowercase — using a Dictionary
    /// avoids that whole class of trouble.
    /// </summary>
    private static Dictionary<string, object> BuildRelationship(RelationshipEntity r, long me)
    {
        var other = r.RequesterId == me ? r.TargetId : r.RequesterId;
        // ReciprocalStatus enum: 0=None, 1=ByMe, 2=ByThem, 3=Both.
        // Our schema only tracks "by me" (the requester's perspective)
        // so we can answer ByMe / None; ByThem / Both would require
        // looking up the OTHER direction's row too. Cheap extra query
        // omitted — the watch's UI only consumes the ByMe bit.
        var mineDir = r.RequesterId == me;
        var muted    = mineDir && r.Muted     ? 1 : 0;
        var ignored  = mineDir && r.Ignored   ? 1 : 0;
        var favored  = mineDir && r.Favorited ? 1 : 0;
        return new()
        {
            ["PlayerID"]         = (int)other,
            ["RelationshipType"] = MapType(r, me),
            ["Muted"]            = muted,
            ["Ignored"]          = ignored,
            ["Favorited"]        = favored,
        };
    }

    /// <summary>Merge all rows for one pair (up to two — one per direction)
    /// into a single wire object from <paramref name="me"/>'s view. The
    /// relationship type comes from whichever row defines it (Blocked &gt;
    /// Friend &gt; Pending); the favorite/mute/ignore bits are the caller's
    /// own, read from the row where the caller is the requester. Without this
    /// a favorite the caller set on a friendship the OTHER player initiated
    /// lands on a separate row and is dropped by the watch (its list is keyed
    /// by PlayerID, so a duplicate id loses).</summary>
    private static Dictionary<string, object> BuildMerged(long me, long other, List<RelationshipEntity> pair)
    {
        var statusRow =
            pair.FirstOrDefault(r => r.Status == EntityStatus.Blocked)
            ?? pair.FirstOrDefault(r => r.Status == EntityStatus.Friend)
            ?? pair.FirstOrDefault(r => r.Status is EntityStatus.PendingSent or EntityStatus.PendingReceived)
            ?? pair[0];
        var mineRow = pair.FirstOrDefault(r => r.RequesterId == me);
        return new()
        {
            ["PlayerID"]         = (int)other,
            ["RelationshipType"] = MapType(statusRow, me),
            ["Muted"]            = mineRow is { Muted: true }     ? 1 : 0,
            ["Ignored"]          = mineRow is { Ignored: true }   ? 1 : 0,
            ["Favorited"]        = mineRow is { Favorited: true } ? 1 : 0,
        };
    }

    /// <summary>"None" relationship for a target the caller has nothing
    /// on file with — used as a no-op success response so the watch's
    /// Relationship.Deserialize stays satisfied.</summary>
    private static Dictionary<string, object> EmptyRelationship(long other) => new()
    {
        ["PlayerID"]         = (int)other,
        ["RelationshipType"] = RT_None,
        ["Muted"]            = RS_None,
        ["Ignored"]          = RS_None,
        ["Favorited"]        = RS_None,
    };
}