namespace WebDrop.Core;

public sealed partial class ChannelService
{
    public void AccountProfileChanged(string username)
    {
        foreach (var id in store.Read(tx => tx.ListAccountSpaces(username, clock.NowMs))) events.SettingsChanged(id);
    }
    public IReadOnlyList<ChannelInfo> AccountSpaces(string username) => store.Read(tx => tx.ListAccountSpaces(username, clock.NowMs).Select(id =>
    {
        var channel = tx.GetChannel(id)!;
        var role = tx.GetChannelMember(id, username)?.Role == "owner" ? Role.Owner : channel.WriteHash is not null ? Role.Write : Role.Read;
        return ToInfo(channel, tx.CountMembers(id), new Principal(role, username));
    }).ToList());
    private static WorkspaceState NewWorkspace(string username, long now)
    {
        var id = Guid.NewGuid().ToString();
        var state = new WorkspaceState { Revision = 1, DefaultChannelId = id, Channels = [new WorkspaceChannel { Id = id, Name = "常规", CreatedAt = now, CreatedBy = username }] };
        EnsureDefaultRole(state, now);
        return state;
    }
    /// <summary>补上默认身份组(只补一次)。读取时只在内存里补,下一次写入才落库</summary>
    private static void EnsureDefaultRole(WorkspaceState state, long now)
    {
        if (state.RolesSeeded) return;
        if (!state.Roles.Any(r => r.Id == WorkspaceRole.DefaultId)) state.Roles.Insert(0, WorkspaceRole.CreateDefault(now));
        state.RolesSeeded = true;
    }
    public WorkspaceState GetWorkspace(Id16 id, Credentials creds) => store.Read(tx =>
    {
        var (space, principal) = Authenticate(tx, id, creds, Membership.Required);
        var state = tx.GetWorkspace(id) ?? new WorkspaceState();
        EnsureDefaultRole(state, clock.NowMs);
        if (principal.AccountName != space.CreatorAccount)
        {
            var crypto = tx.GetWorkspaceCrypto(id);
            var grants = crypto.Access.Where(a => a.Username == principal.AccountName).ToList();
            var ids = grants.Where(a => a.ChatRead || a.FilesRead).Select(a => a.ChannelId).ToHashSet();
            state.Channels.RemoveAll(c => !ids.Contains(c.Id));
            foreach (var workspaceChannel in state.Channels)
            {
                var grant = grants.Find(a => a.ChannelId == workspaceChannel.Id);
                if (grant is null || !grant.FilesRead && !grant.FilesUpload) workspaceChannel.FileBytes = 0;
            }
            state.Folders.RemoveAll(f => !ids.Contains(f.ThreadId));
            state.Locations.RemoveAll(l => !Id16.TryParse(l.ItemId, out var itemId) || !CanReadObject(tx, space, principal, itemId));
        }
        state.Locations = state.Locations.Where(l => Id16.TryParse(l.ItemId, out var itemId) && tx.GetItem(id, itemId) is { } item && item.ExpiresAt > clock.NowMs).ToList();
        return state;
    });
    private WorkspaceState ChangeWorkspace(Id16 id, Credentials creds, Action<IResourceTx, WorkspaceState, Principal> change, bool requireAccount = true, string? permission = null)
    {
        var state = store.Write(tx =>
        {
            var (channel, principal) = Authenticate(tx, id, creds, Membership.Required);
            var current = tx.GetWorkspace(id) ?? new WorkspaceState();
            EnsureDefaultRole(current, clock.NowMs);
            // 被授予对应权限的身份组成员可以代行,不要求频道开放成员上传
            bool delegated = permission is not null && principal.Role != Role.Owner && HasWorkspacePermission(current, principal, permission);
            if (requireAccount && principal.Role != Role.Owner && !delegated) throw new WebDropException(ErrorCode.Forbidden);
            if (!delegated && !ChannelPolicy.CanWrite(channel, principal)) throw new WebDropException(ErrorCode.Forbidden);
            current.Locations = current.Locations.Where(l => Id16.TryParse(l.ItemId, out var itemId) && tx.GetItem(id, itemId) is not null).ToList();
            change(tx, current, principal);
            ValidateWorkspace(current);
            current.Revision++;
            tx.PutWorkspace(id, current);
            return current;
        });
        events.SettingsChanged(id);
        return state;
    }
    public (WorkspaceState State, WorkspaceChannel Channel) CreateWorkspaceChannelResult(Id16 id, Credentials creds, string name, string? groupId)
    {
        WorkspaceChannel? created = null;
        var state = ChangeWorkspace(id, creds, (_, workspace, principal) =>
        {
            created = new WorkspaceChannel { Id = Guid.NewGuid().ToString(), Name = WorkspaceName(name), GroupId = groupId, CreatedAt = clock.NowMs, CreatedBy = principal.AccountName! };
            workspace.Channels.Add(created);
        });
        return (state, created!);
    }
    public WorkspaceState CreateWorkspaceChannel(Id16 id, Credentials creds, string name, string? groupId) => CreateWorkspaceChannelResult(id, creds, name, groupId).State;
    public WorkspaceState RenameWorkspaceChannel(Id16 id, Credentials creds, string channelId, string name) => ChangeWorkspace(id, creds, (_, state, _) =>
        FindChannel(state, channelId).Name = WorkspaceName(name), permission: WorkspacePermission.ManageStructure);
    public WorkspaceState GroupWorkspaceChannel(Id16 id, Credentials creds, string channelId, string? groupId) => ChangeWorkspace(id, creds, (_, state, _) =>
        FindChannel(state, channelId).GroupId = groupId, permission: WorkspacePermission.ManageStructure);
    public (WorkspaceState State, WorkspaceGroup Group) CreateWorkspaceGroupResult(Id16 id, Credentials creds, string name)
    {
        WorkspaceGroup? created = null;
        var state = ChangeWorkspace(id, creds, (_, workspace, _) =>
        {
            created = new WorkspaceGroup { Id = Guid.NewGuid().ToString(), Name = WorkspaceName(name), CreatedAt = clock.NowMs };
            workspace.Groups.Add(created);
        }, permission: WorkspacePermission.ManageStructure);
        return (state, created!);
    }
    public WorkspaceState CreateWorkspaceGroup(Id16 id, Credentials creds, string name) => CreateWorkspaceGroupResult(id, creds, name).State;
    public WorkspaceState RenameWorkspaceGroup(Id16 id, Credentials creds, string groupId, string name) => ChangeWorkspace(id, creds, (_, state, _) =>
        (state.Groups.Find(g => g.Id == groupId) ?? throw new WebDropException(ErrorCode.NotFound)).Name = WorkspaceName(name), permission: WorkspacePermission.ManageStructure);
    /// <summary>删除分组:组里的频道回到未分组,频道本身和内容都不动</summary>
    public WorkspaceState DeleteWorkspaceGroup(Id16 id, Credentials creds, string groupId) => ChangeWorkspace(id, creds, (_, state, _) =>
    {
        var group = state.Groups.Find(g => g.Id == groupId) ?? throw new WebDropException(ErrorCode.NotFound);
        foreach (var channel in state.Channels.Where(c => c.GroupId == groupId)) channel.GroupId = null;
        state.Groups.Remove(group);
    }, permission: WorkspacePermission.ManageStructure);
    // ───── 身份组(只有空间主能增删改、分配成员) ─────
    public static bool HasWorkspacePermission(WorkspaceState? state, Principal principal, string permission) =>
        principal.Role == Role.Owner
        || principal.AccountName is { } account && state?.Roles.Any(r => r.Members.Contains(account) && r.Permissions.Contains(permission)) == true;
    private static string? RoleLabel(string? value)
    {
        value = value?.Trim();
        if (string.IsNullOrEmpty(value)) return null;
        if (value.Length > 12 || value.Any(char.IsControl)) throw new WebDropException(ErrorCode.BadRequest);
        return value;
    }
    private static void ApplyRole(WorkspaceRole role, string name, string? prefix, string? suffix, string? color, IReadOnlyList<string> permissions)
    {
        if (color is not null && !WorkspacePermission.Colors.Contains(color)) throw new WebDropException(ErrorCode.BadRequest);
        if (permissions.Any(p => !WorkspacePermission.All.Contains(p))) throw new WebDropException(ErrorCode.BadRequest);
        role.Name = WorkspaceName(name); role.Prefix = RoleLabel(prefix); role.Suffix = RoleLabel(suffix); role.Color = color;
        role.Permissions = permissions.Distinct().ToList();
    }
    public (WorkspaceState State, WorkspaceRole Role) CreateWorkspaceRoleResult(Id16 id, Credentials creds, string name, string? prefix, string? suffix, string? color, IReadOnlyList<string> permissions)
    {
        WorkspaceRole? created = null;
        var state = ChangeWorkspace(id, creds, (_, workspace, _) =>
        {
            created = new WorkspaceRole { Id = Guid.NewGuid().ToString(), Name = "x", CreatedAt = clock.NowMs };
            ApplyRole(created, name, prefix, suffix, color, permissions);
            workspace.Roles.Add(created);
        });
        return (state, created!);
    }
    public WorkspaceState UpdateWorkspaceRole(Id16 id, Credentials creds, string roleId, string name, string? prefix, string? suffix, string? color, IReadOnlyList<string> permissions) =>
        ChangeWorkspace(id, creds, (_, state, _) => ApplyRole(FindRole(state, roleId), name, prefix, suffix, color, permissions));
    public WorkspaceState DeleteWorkspaceRole(Id16 id, Credentials creds, string roleId) =>
        ChangeWorkspace(id, creds, (_, state, _) => state.Roles.Remove(FindRole(state, roleId)));
    public WorkspaceState SetWorkspaceRoleMembers(Id16 id, Credentials creds, string roleId, IReadOnlyList<string> members) =>
        ChangeWorkspace(id, creds, (tx, state, _) =>
        {
            var role = FindRole(state, roleId);
            var distinct = members.Select(m => m.Trim().ToLowerInvariant()).Distinct().ToList();
            if (distinct.Count > 256) throw new WebDropException(ErrorCode.BadRequest);
            // 只能把已加入空间的账号放进身份组;空间主本来就有全部权限,不必加入
            foreach (var member in distinct)
                if (tx.GetChannelMember(id, member) is not { } row || row.Role == "owner") throw new WebDropException(ErrorCode.BadRequest);
            role.Members = distinct;
        });
    private static WorkspaceRole FindRole(WorkspaceState state, string id) => state.Roles.Find(r => r.Id == id) ?? throw new WebDropException(ErrorCode.NotFound);
    public WorkspaceState CreateWorkspaceFolder(Id16 id, Credentials creds, string threadId, string? parentId, string name) => ChangeWorkspace(id, creds, (_, state, _) =>
        state.Folders.Add(new WorkspaceFolder { Id = Guid.NewGuid().ToString(), ThreadId = threadId, ParentId = parentId, Name = WorkspaceName(name) }));
    public WorkspaceState RenameWorkspaceFolder(Id16 id, Credentials creds, string folderId, string name) => ChangeWorkspace(id, creds, (_, state, _) =>
        (state.Folders.Find(f => f.Id == folderId) ?? throw new WebDropException(ErrorCode.NotFound)).Name = WorkspaceName(name));
    public WorkspaceState MoveWorkspaceItems(Id16 id, Credentials creds, string[] itemIds, string threadId, string? folderId) => ChangeWorkspace(id, creds, (tx, state, principal) =>
    {
        if (itemIds.Length is < 1 or > 100 || itemIds.Distinct().Count() != itemIds.Length) throw new WebDropException(ErrorCode.BadRequest);
        foreach (var itemId in itemIds)
        {
            if (!Id16.TryParse(itemId, out var parsed)) throw new WebDropException(ErrorCode.BadRequest);
            var item = tx.GetItem(id, parsed) ?? throw new WebDropException(ErrorCode.NotFound);
            if ((item.Flags & (FrameFlags.Control | FrameFlags.Snapshot)) != 0) throw new WebDropException(ErrorCode.BadRequest);
            if (principal.Role != Role.Owner && item.AuthorAccount != principal.AccountName) throw new WebDropException(ErrorCode.Forbidden);
            state.Locations.RemoveAll(l => l.ItemId == itemId);
            state.Locations.Add(new WorkspaceLocation { ItemId = itemId, ThreadId = threadId, FolderId = folderId, AuthorAccount = item.AuthorAccount });
        }
    }, requireAccount: false);
    private static WorkspaceChannel FindChannel(WorkspaceState state, string id) => state.Channels.Find(c => c.Id == id) ?? throw new WebDropException(ErrorCode.NotFound);
    private static string WorkspaceName(string name)
    {
        if (string.IsNullOrWhiteSpace(name) || name.Trim().Length > 80 || name.Any(char.IsControl)) throw new WebDropException(ErrorCode.BadRequest);
        return name.Trim();
    }
    private static void ValidateWorkspace(WorkspaceState state)
    {
        if (state.Roles is null || state.Roles.Count > 32 || state.Roles.Any(r => r is null || r.Members is null || r.Permissions is null)) throw new WebDropException(ErrorCode.BadRequest);
        if (state.Channels is null || state.Groups is null || state.Folders is null || state.Locations is null
            || state.Channels.Count > 256 || state.Groups.Count > 128 || state.Folders.Count > 2048 || state.Locations.Count > 10_000)
            throw new WebDropException(ErrorCode.BadRequest);
        if (state.Channels.Any(c => c is null) || state.Groups.Any(g => g is null) || state.Folders.Any(f => f is null) || state.Locations.Any(l => l is null)) throw new WebDropException(ErrorCode.BadRequest);
        var allIds = state.Channels.Select(c => c.Id).Concat(state.Groups.Select(g => g.Id)).Concat(state.Folders.Select(f => f.Id)).Concat(state.Roles.Select(r => r.Id)).ToArray();
        if (allIds.Any(id => !Guid.TryParseExact(id, "D", out _)) || allIds.Distinct().Count() != allIds.Length) throw new WebDropException(ErrorCode.BadRequest);
        foreach (var group in state.Groups) group.Name = WorkspaceName(group.Name);
        foreach (var channel in state.Channels)
        {
            channel.Name = WorkspaceName(channel.Name);
            if (channel.GroupId is not null && !state.Groups.Any(g => g.Id == channel.GroupId)) throw new WebDropException(ErrorCode.BadRequest);
        }
        foreach (var folder in state.Folders)
        {
            folder.Name = WorkspaceName(folder.Name);
            _ = FindChannel(state, folder.ThreadId);
            var visited = new HashSet<string> { folder.Id };
            for (var parentId = folder.ParentId; parentId is not null;)
            {
                var parent = state.Folders.Find(f => f.Id == parentId && f.ThreadId == folder.ThreadId);
                if (parent is null || !visited.Add(parent.Id)) throw new WebDropException(ErrorCode.BadRequest);
                parentId = parent.ParentId;
            }
        }
        if (state.Locations.Select(l => l.ItemId).Distinct().Count() != state.Locations.Count) throw new WebDropException(ErrorCode.BadRequest);
        foreach (var location in state.Locations)
        {
            _ = FindChannel(state, location.ThreadId);
            if (location.FolderId is not null && !state.Folders.Any(f => f.Id == location.FolderId && f.ThreadId == location.ThreadId)) throw new WebDropException(ErrorCode.BadRequest);
        }
    }
}