using WxAgent.Core;

namespace WxAgent.Windows;

public static class WechatContactDbReader
{
    public static async Task<AccountKeySet> LoadAccountAsync(string? accountId = null, string? keyFile = null, CancellationToken cancellationToken = default)
    {
        var accounts = await DatabaseKeyStore.LoadAsync(keyFile, cancellationToken).ConfigureAwait(false);
        var matches = accounts.Where(account => accountId is null ||
            string.Equals(account.AccountRootFingerprint, accountId, StringComparison.OrdinalIgnoreCase)).ToArray();
        if (matches.Length == 0)
            throw new WxAgentException(WxAgentErrorCode.DatabaseKeyNotFound, "No matching account was found in the key store; run db scan first.");
        if (matches.Length != 1)
            throw new WxAgentException(WxAgentErrorCode.InvalidArgument, "Select one account fingerprint explicitly; multiple cached accounts match.");
        return matches[0];
    }

    public static async Task<DatabaseAccountIdentity?> ReadAccountIdentityAsync(AccountKeySet account,
        CancellationToken cancellationToken = default)
    {
        var storageDirectory = new DirectoryInfo(account.AccountRootPath);
        var directoryName = storageDirectory.Name.Equals("db_storage", StringComparison.OrdinalIgnoreCase)
            ? storageDirectory.Parent?.Name ?? storageDirectory.Name
            : storageDirectory.Name;
        var separator = directoryName.LastIndexOf('_');
        var candidates = new[]
        {
            directoryName,
            separator > 0 ? directoryName[..separator] : directoryName
        }.Where(candidate => !string.IsNullOrWhiteSpace(candidate)).Distinct(StringComparer.OrdinalIgnoreCase);
        foreach (var candidate in candidates)
        {
            var page = await ReadPageAsync(account, 10000, 0, candidate, false, cancellationToken).ConfigureAwait(false);
            var exact = page.Contacts.Where(contact => string.Equals(contact.Username, candidate, StringComparison.OrdinalIgnoreCase)).ToArray();
            if (exact.Length == 1)
            {
                var contact = exact[0];
                return new DatabaseAccountIdentity(account.AccountRootFingerprint, contact.Username, contact.DisplayName);
            }
        }
        return null;
    }

    public static async Task<WechatContactPage> ReadPageAsync(AccountKeySet account, int limit = 200, int offset = 0,
        string? contains = null, bool? groupsOnly = null, CancellationToken cancellationToken = default)
    {
        cancellationToken.ThrowIfCancellationRequested();
        var parameters = WechatContactQuery.Parameters(limit, offset, contains, groupsOnly);
        var database = RequireContactDatabase(account);
        // The shared reader revalidates page-1 HMAC on every open and enforces read-only mode.
        var rows = await SqlCipherDatabaseReader.QueryRowsAsync(ContactDatabasePath(account), database.EncKey,
            WechatContactQuery.Sql, parameters, cancellationToken).ConfigureAwait(false);
        var contacts = rows.Select(row => new WechatDatabaseContact(
            row.GetValueOrDefault("username") as string ?? throw new WxAgentException(
                WxAgentErrorCode.DatabaseOpenFailed, "A contact row has no stable username."),
            row.GetValueOrDefault("nick_name") as string, row.GetValueOrDefault("remark") as string,
            row.GetValueOrDefault("small_head_url") as string)).ToArray();
        return WechatContactQuery.Page(contacts, limit, offset);
    }

    public static async Task<WechatGroupMemberPage> ReadGroupMembersPageAsync(AccountKeySet account, string group,
        int limit = 500, int offset = 0, CancellationToken cancellationToken = default)
    {
        cancellationToken.ThrowIfCancellationRequested();
        ArgumentException.ThrowIfNullOrWhiteSpace(group);
        var groups = await ReadPageAsync(account, 10000, contains: group, groupsOnly: true,
            cancellationToken: cancellationToken).ConfigureAwait(false);
        if (groups.HasMore)
            throw new WxAgentException(WxAgentErrorCode.InvalidOperationState, "Group lookup is truncated; use a stable @chatroom username.");
        var exact = groups.Contacts.Where(item => item.Username == group || item.DisplayName == group).ToArray();
        var selected = WechatOperationPolicy.RequireUnique(exact, "database group");
        var parameters = WechatGroupMemberQuery.Parameters(selected.Username, limit, offset);
        var database = RequireContactDatabase(account);
        var rows = await SqlCipherDatabaseReader.QueryRowsAsync(ContactDatabasePath(account), database.EncKey,
            WechatGroupMemberQuery.Sql, parameters, cancellationToken).ConfigureAwait(false);
        var members = rows.Select(row =>
        {
            var id = Convert.ToInt64(row.GetValueOrDefault("member_id"), System.Globalization.CultureInfo.InvariantCulture);
            var username = row.GetValueOrDefault("username") as string ?? throw new WxAgentException(
                WxAgentErrorCode.DatabaseOpenFailed, "A group-member row has no stable username.");
            var remark = row.GetValueOrDefault("remark") as string;
            var nickname = row.GetValueOrDefault("nick_name") as string;
            var owner = Convert.ToString(row.GetValueOrDefault("owner"), System.Globalization.CultureInfo.InvariantCulture);
            var displayName = !string.IsNullOrWhiteSpace(remark) ? remark : !string.IsNullOrWhiteSpace(nickname) ? nickname : username;
            var isOwner = string.Equals(owner, username, StringComparison.Ordinal) ||
                long.TryParse(owner, System.Globalization.NumberStyles.None, System.Globalization.CultureInfo.InvariantCulture, out var ownerId) && ownerId == id;
            return new WechatDatabaseGroupMember(id, username, displayName, isOwner);
        }).ToArray();
        return WechatGroupMemberQuery.Page(selected.Username, members, limit, offset);
    }

    private static DatabaseKeyEvidence RequireContactDatabase(AccountKeySet account)
    {
        var databases = account.Databases.Where(item =>
            string.Equals(item.RelativePath.Replace('\\', '/'), "contact/contact.db", StringComparison.OrdinalIgnoreCase)).ToArray();
        if (databases.Length != 1)
            throw new WxAgentException(WxAgentErrorCode.DatabaseKeyNotFound, "Exactly one contact.db key is required for the selected account.");
        return databases[0];
    }

    private static string ContactDatabasePath(AccountKeySet account) =>
        Path.GetFullPath(Path.Combine(account.AccountRootPath, "contact", "contact.db"));
}