using System.Globalization;

namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb;

/// <summary>
///     Table names and DDL for the QuestDB backend (T0-confirmed against QuestDB 10.0.1). The TTL clause sits
///     between <c>PARTITION BY</c> and <c>WAL</c> and is an inlined integer (QuestDB cannot parameterise it).
///     Prefixes are regex-validated by the caller; these builders also refuse an invalid one.
/// </summary>
internal static class QuestDbTables
{
    /// <summary>Base name of the sample table (prefix + this).</summary>
    public const string SampleBase = "sample";
    /// <summary>Base name of the event table.</summary>
    public const string EventBase = "event";
    /// <summary>Base name of the tag catalog table.</summary>
    public const string TagBase = "tag";
    /// <summary>Base name of the Part 11 modification-trail table (#668).</summary>
    public const string SampleModifiedBase = "sample_modified";

    /// <summary>The fixed designated timestamp of every <c>tag</c> row, which makes the dedup key an upsert by name.</summary>
    public static readonly DateTime TagEpoch = DateTime.UnixEpoch;

    /// <summary>The prefixed sample table name.</summary>
    public static string Sample(string prefix) => Name(prefix, SampleBase);
    /// <summary>The prefixed event table name.</summary>
    public static string Event(string prefix) => Name(prefix, EventBase);
    /// <summary>The prefixed tag table name.</summary>
    public static string Tag(string prefix) => Name(prefix, TagBase);
    /// <summary>The prefixed modification-trail table name.</summary>
    public static string SampleModified(string prefix) => Name(prefix, SampleModifiedBase);

    /// <summary>All four table names in creation order.</summary>
    public static string[] All(string prefix) => [Sample(prefix), Event(prefix), Tag(prefix), SampleModified(prefix)];

    /// <summary>
    ///     The tables that carry a TTL (sample, event and the modification trail, which ages out with the samples it
    ///     describes; the tag catalog never expires).
    /// </summary>
    public static string[] Expiring(string prefix) => [Sample(prefix), Event(prefix), SampleModified(prefix)];

    /// <summary>
    ///     <c>CREATE TABLE IF NOT EXISTS</c> for the sample table. <c>tag</c> carries a symbol (bitmap) index (#683): every
    ///     read filters on one tag, and without the index QuestDB answers a <c>tag = x</c> seek by scanning the tag column of
    ///     every partition in the time range — the data-range lookups (<see cref="QuestDbAggregateQueries.EarliestSample"/> /
    ///     <c>LatestSample</c>) of a stopped or late-starting tag then scan every partition on one side of the window.
    ///     A table created before #683 gains the index through <see cref="AddTagIndex"/>.
    /// </summary>
    public static string CreateSample(string prefix, int? retentionDays) =>
        $"CREATE TABLE IF NOT EXISTS {Sample(prefix)} (ts TIMESTAMP, tag SYMBOL INDEX, kind BYTE, num_value DOUBLE, " +
        "int_value LONG, str_value VARCHAR, status LONG, deleted BOOLEAN, server_ts TIMESTAMP) " +
        $"TIMESTAMP(ts) PARTITION BY DAY{Ttl(retentionDays)} WAL DEDUP UPSERT KEYS(ts, tag)";

    /// <summary><c>CREATE TABLE IF NOT EXISTS</c> for the event table.</summary>
    public static string CreateEvent(string prefix, int? retentionDays) =>
        $"CREATE TABLE IF NOT EXISTS {Event(prefix)} (ts TIMESTAMP, event_id VARCHAR, source SYMBOL, alarm_id VARCHAR, " +
        "alarm_name VARCHAR, alarm_type_name VARCHAR, severity INT, event_kind VARCHAR, message VARCHAR, " +
        "user_name VARCHAR, comment VARCHAR, received_utc TIMESTAMP) " +
        $"TIMESTAMP(ts) PARTITION BY DAY{Ttl(retentionDays)} WAL DEDUP UPSERT KEYS(ts, event_id)";

    /// <summary><c>CREATE TABLE IF NOT EXISTS</c> for the tag catalog (YEAR partitions, no TTL ever).</summary>
    public static string CreateTag(string prefix) =>
        $"CREATE TABLE IF NOT EXISTS {Tag(prefix)} (ts TIMESTAMP, name SYMBOL, data_type BYTE, eng_unit VARCHAR, " +
        "description VARCHAR, updated_utc TIMESTAMP) TIMESTAMP(ts) PARTITION BY YEAR WAL DEDUP UPSERT KEYS(ts, name)";

    /// <summary>
    ///     <c>CREATE TABLE IF NOT EXISTS</c> for the Part 11 modification trail (#668): one row per sample a HistoryUpdate
    ///     inserted, replaced or deleted, carrying the PRIOR value (NULL kind/value/status for an insert). <c>ts</c> is the
    ///     sample's source time (so the TTL ages it out with the samples); <c>modified_id</c> orders the trail within one
    ///     source time. Append-only: no DEDUP, never updated or deleted.
    /// </summary>
    public static string CreateSampleModified(string prefix, int? retentionDays) =>
        $"CREATE TABLE IF NOT EXISTS {SampleModified(prefix)} (ts TIMESTAMP, tag SYMBOL, modified_id LONG, " +
        "modification_ts TIMESTAMP, update_type BYTE, principal VARCHAR, api_key_id VARCHAR, kind BYTE, num_value DOUBLE, " +
        "int_value LONG, str_value VARCHAR, status LONG, server_ts TIMESTAMP) " +
        $"TIMESTAMP(ts) PARTITION BY DAY{Ttl(retentionDays)} WAL";

    /// <summary>The four CREATE statements in creation order (parallel to <see cref="All"/>).</summary>
    public static string[] CreateAll(string prefix, int? retentionDays) =>
        [CreateSample(prefix, retentionDays), CreateEvent(prefix, retentionDays), CreateTag(prefix),
            CreateSampleModified(prefix, retentionDays)];

    /// <summary>
    ///     <c>ALTER TABLE t ALTER COLUMN tag ADD INDEX</c> — the #683 migration of a sample table created without the tag
    ///     index. A WAL transaction (visible once applied); re-issuing it on an indexed column is a harmless no-op (the table
    ///     is not suspended), so two nodes booting together may both send it.
    /// </summary>
    public static string AddTagIndex(string table) => $"ALTER TABLE {table} ALTER COLUMN tag ADD INDEX";

    /// <summary>
    ///     Whether <paramref name="table"/>'s <c>tag</c> column is indexed: one row, one BOOLEAN column, no row when the
    ///     table or column is missing. The name is inlined (<c>table_columns()</c> takes a constant); it is always a
    ///     prefix-validated name built here.
    /// </summary>
    public static string TagIndexedQuery(string table) =>
        $"SELECT indexed FROM table_columns('{table}') WHERE \"column\" = 'tag'";

    /// <summary><c>ALTER TABLE t SET TTL n DAYS</c>; <c>null</c> removes the TTL (<c>SET TTL 0 DAYS</c>).</summary>
    public static string AlterTtl(string table, int? retentionDays) =>
        $"ALTER TABLE {table} SET TTL {(retentionDays ?? 0).ToString(CultureInfo.InvariantCulture)} DAYS";

    /// <summary>
    ///     Converts a <c>tables()</c> <c>ttlValue</c>/<c>ttlUnit</c> pair to hours. QuestDB normalises the unit (7 days
    ///     reads back as <c>1 WEEK</c>), so equality is judged in hours. An unrecognised unit returns -1 (never equal to
    ///     a wanted value, so the bootstrapper re-applies the TTL).
    /// </summary>
    public static long TtlHours(long value, string? unit) => (unit ?? "").ToUpperInvariant() switch
    {
        "HOUR" => value,
        "DAY" => value * 24,
        "WEEK" => value * 168,
        _ => value == 0 ? 0 : -1,
    };

    private static string Ttl(int? days) =>
        days is { } d ? $" TTL {d.ToString(CultureInfo.InvariantCulture)} DAYS" : "";

    private static string Name(string prefix, string baseName)
    {
        if (!QuestDbHistorianOptions.IsValidPrefix(prefix))
            throw new ArgumentException("Invalid table prefix.", nameof(prefix));
        return prefix + baseName;
    }
}