using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using HC_APTBS.Models;

namespace HC_APTBS.Services
{
    /// <summary>
    /// Provides KWP2000 / KW1281 diagnostics operations over the ISO K-Line
    /// via an FTDI USB-to-K-Line adapter.
    /// </summary>
    public interface IKwpService
    {
        // ── Session lifecycle ─────────────────────────────────────────────────────

        /// <summary>Current state of the persistent K-Line session.</summary>
        KLineConnectionState KLineState { get; }

        /// <summary>
        /// Raised whenever the K-Line session state transitions.
        /// Fires on a background thread; consumers must marshal to the UI thread.
        /// </summary>
        event Action<KLineConnectionState>? KLineStateChanged;

        /// <summary>
        /// Opens a persistent K-Line session: performs 5-baud slow-init,
        /// reads ECU info, then starts a background keep-alive loop (~1 s interval).
        /// </summary>
        /// <param name="port">FTDI serial number or COM port identifier.</param>
        /// <param name="ct">Cancellation token.</param>
        Task ConnectAsync(string port, CancellationToken ct = default);

        /// <summary>
        /// Stops the keep-alive loop, sends EndCommunication to the ECU,
        /// and disposes the FTDI interface.
        /// </summary>
        void Disconnect();

        // ── Progress reporting ────────────────────────────────────────────────────

        /// <summary>
        /// Raised during long operations to report completion percentage and a status message.
        /// Always marshalled to the UI thread by the implementation.
        /// </summary>
        event Action<int, string>? ProgressChanged;

        // ── Full ECU read ─────────────────────────────────────────────────────────

        /// <summary>
        /// Connects to the pump ECU over K-Line and reads all available identification data,
        /// fault codes, DFI value, serial number, and software versions.
        /// </summary>
        /// <param name="port">FTDI serial number or COM port identifier.</param>
        /// <param name="pumpVersion">KWP protocol variant (0=V1, 1=V2, 2=V3/V4).</param>
        /// <param name="ct">Cancellation token.</param>
        /// <returns>
        /// Dictionary with keys from <see cref="HC_APTBS.Models.KlineKeys"/>.
        /// The <c>result</c> key is "1" on success, "0" on failure.
        /// </returns>
        Task<Dictionary<string, string>> ReadAllInfoAsync(
            string port, int pumpVersion, CancellationToken ct = default);

        // ── DTC operations ────────────────────────────────────────────────────────

        /// <summary>Reads all current diagnostic trouble codes from the ECU.</summary>
        /// <param name="port">FTDI serial number or COM port identifier.</param>
        /// <param name="ct">Cancellation token.</param>
        /// <returns>Formatted fault code string, or "No fault codes".</returns>
        Task<string> ReadFaultCodesAsync(string port, CancellationToken ct = default);

        /// <summary>Clears all diagnostic trouble codes and returns the post-clear state.</summary>
        /// <param name="port">FTDI serial number or COM port identifier.</param>
        /// <param name="ct">Cancellation token.</param>
        /// <returns>Post-clear fault code string.</returns>
        Task<string> ClearFaultCodesAsync(string port, CancellationToken ct = default);

        // ── DFI calibration ───────────────────────────────────────────────────────

        /// <summary>Reads the current DFI calibration angle from EEPROM address 0x0044.</summary>
        /// <param name="port">FTDI serial number or COM port identifier.</param>
        /// <param name="ct">Cancellation token.</param>
        /// <returns>DFI value in degrees as a formatted string.</returns>
        Task<string> ReadDfiAsync(string port, CancellationToken ct = default);

        /// <summary>
        /// Writes a new DFI calibration angle to EEPROM address 0x0044.
        /// </summary>
        /// <param name="port">FTDI serial number or COM port identifier.</param>
        /// <param name="dfi">Target DFI angle (degrees, range ±1.45°).</param>
        /// <param name="version">KWP protocol variant (selects the authentication password).</param>
        /// <param name="ct">Cancellation token.</param>
        /// <returns>Verified DFI value read back from EEPROM after the write.</returns>
        Task<string> WriteDfiAsync(
            string port, float dfi, int version, CancellationToken ct = default);

        /// <summary>
        /// Writes DFI to EEPROM, then triggers a pump power cycle via
        /// <see cref="PumpDisconnectRequested"/> / <see cref="PumpReconnectRequested"/>
        /// to activate the new calibration.
        /// </summary>
        Task<string> WriteDfiAndRestartAsync(
            string port, float dfi, int version, CancellationToken ct = default);

        // ── Device detection ──────────────────────────────────────────────────────

        /// <summary>
        /// Enumerates connected FTDI USB devices and returns the serial number of the
        /// first one found, or <see langword="null"/> if none are connected.
        /// </summary>
        string? DetectKLinePort();

        /// <summary>
        /// The FTDI serial number of the device that is currently holding an open
        /// K-Line session, or <see langword="null"/> when no session is active.
        /// </summary>
        string? ConnectedPort { get; }

        // ── Mid-read notifications ────────────────────────────────────────────

        /// <summary>
        /// Raised during <see cref="ReadAllInfoAsync"/> as soon as the pump identifier
        /// string has been read from ROM, before the full read completes.
        /// Fires on a background thread; consumers must marshal to the UI thread.
        /// </summary>
        event Action<string>? PumpIdentified;

        /// <summary>
        /// Raised during <see cref="ReadAllInfoAsync"/> when the DFI calibration
        /// value has been read from EEPROM. Parameter is the DFI angle in degrees.
        /// Fires on a background thread; consumers must marshal to the UI thread.
        /// </summary>
        event Action<double>? DfiRead;

        // ── Fast immobilizer unlock ───────────────────────────────────────────────

        /// <summary>
        /// Attempts a fast immobilizer unlock by sending a KWP custom command
        /// over an existing K-Line session. The RAM address byte written by the
        /// command is selected by <paramref name="unlockType"/>: <c>1</c> → <c>0xA8</c>,
        /// <c>2</c> → <c>0xE8</c>. Any other value is rejected and returns
        /// <see langword="false"/>.
        /// </summary>
        /// <param name="unlockType">Pump unlock variant (1 or 2).</param>
        /// <returns>
        /// <see langword="true"/> when the command was acknowledged,
        /// <see langword="false"/> on NAK, no active session, or unsupported type.
        /// </returns>
        Task<bool> TryFastUnlockAsync(int unlockType);

        // ── Raw custom KWP packet (developer use) ─────────────────────────────────

        /// <summary>
        /// Sends a raw KWP1281 custom packet over the persistent K-Line session and
        /// returns the bytes of every response packet. The supplied <paramref name="payload"/>
        /// is the title byte plus body — framing (length + counter + end byte) is added
        /// by the lower-level transport.
        ///
        /// <para>Returns an empty list when no session is active or the send fails.
        /// Used by the Developer Tools page; never called from production paths.</para>
        /// </summary>
        /// <param name="payload">Packet bytes excluding length/counter/end framing.</param>
        /// <param name="ct">Cancellation token.</param>
        /// <returns>Each response packet's full byte sequence (length…end inclusive).</returns>
        Task<IReadOnlyList<byte[]>> SendRawCustomAsync(byte[] payload, CancellationToken ct = default);

        /// <summary>
        /// Reads <paramref name="count"/> bytes from EEPROM starting at <paramref name="address"/>
        /// over the persistent K-Line session (KWP <c>ReadEeprom</c> command 0x19).
        /// Returns an empty list when no session is active or the ECU returns NAK.
        /// Used by the Developer Tools page's dumper; max 13 bytes per call.
        /// </summary>
        Task<IReadOnlyList<byte>> ReadEepromAsync(ushort address, byte count, CancellationToken ct = default);

        /// <summary>
        /// Reads <paramref name="count"/> bytes from ROM/EEPROM starting at <paramref name="address"/>
        /// over the persistent K-Line session (KWP <c>ReadRomEeprom</c> command 0x03).
        /// Valid range 0x0000–0x9FFF. Returns an empty list when no session is active or
        /// the ECU returns NAK. Used by the Developer Tools page's dumper; max 13 bytes per call.
        /// </summary>
        Task<IReadOnlyList<byte>> ReadRomEepromAsync(ushort address, byte count, CancellationToken ct = default);

        // ── BIP status ────────────────────────────────────────────────────────────

        /// <summary>
        /// Reads the 16-bit BIP status word from ECU RAM address <c>0x0106</c>
        /// (<c>ADR-S_BIP_HW_UW</c>) over the persistent K-Line session.
        /// Returns <see langword="null"/> when no session is active or if the read fails.
        /// </summary>
        /// <param name="ct">Cancellation token.</param>
        Task<ushort?> ReadBipStatusAsync(CancellationToken ct = default);

        /// <summary>
        /// Raised after a successful <see cref="ReadBipStatusAsync"/> call with the
        /// raw 16-bit BIP status word. Fires on a background thread;
        /// consumers must marshal to the UI thread.
        /// </summary>
        event Action<ushort>? BipStatusRead;

        // ── Power cycle callbacks ─────────────────────────────────────────────────

        /// <summary>
        /// Raised when the service needs the bench to cut power to the pump
        /// (e.g. after a DFI write) before reconnecting.
        /// </summary>
        event Action? PumpDisconnectRequested;

        /// <summary>
        /// Raised after <see cref="PumpDisconnectRequested"/> when the service needs
        /// the bench to restore power and re-establish the K-Line session.
        /// </summary>
        event Action? PumpReconnectRequested;
    }
}