#pragma once
// OBD-II PID constants and decode helpers (SAE J1979)
// Covers the most common Mode 01 (current data) PIDs.

#include <Arduino.h>

namespace obd2 {

// --- Diagnostic modes ---
constexpr uint8_t MODE_CURRENT      = 0x01;  // current data
constexpr uint8_t MODE_FREEZE       = 0x02;  // freeze frame
constexpr uint8_t MODE_DTC          = 0x03;  // stored DTCs
constexpr uint8_t MODE_CLEAR_DTC    = 0x04;  // clear DTCs
constexpr uint8_t MODE_O2_TEST      = 0x05;  // O2 sensor monitoring
constexpr uint8_t MODE_TEST_RESULTS = 0x06;  // on-board monitoring test results
constexpr uint8_t MODE_PENDING_DTC  = 0x07;  // pending DTCs
constexpr uint8_t MODE_CONTROL      = 0x08;  // control of on-board system
constexpr uint8_t MODE_VEHICLE_INFO = 0x09;  // vehicle information (VIN, etc.)
constexpr uint8_t MODE_PERMANENT_DTC = 0x0A; // permanent DTCs

// --- Mode 01 PIDs ---
constexpr uint8_t PID_SUPPORTED_01_20   = 0x00;  // supported PIDs [01-20]
constexpr uint8_t PID_DTC_STATUS        = 0x01;  // monitor status since DTCs cleared
constexpr uint8_t PID_FUEL_STATUS       = 0x03;  // fuel system status
constexpr uint8_t PID_ENGINE_LOAD       = 0x04;  // calculated engine load (%)
constexpr uint8_t PID_COOLANT_TEMP      = 0x05;  // engine coolant temperature (C)
constexpr uint8_t PID_SHORT_FUEL_TRIM_1 = 0x06;  // short term fuel trim bank 1 (%)
constexpr uint8_t PID_LONG_FUEL_TRIM_1  = 0x07;  // long term fuel trim bank 1 (%)
constexpr uint8_t PID_INTAKE_PRESSURE   = 0x0B;  // intake manifold pressure (kPa)
constexpr uint8_t PID_RPM               = 0x0C;  // engine RPM
constexpr uint8_t PID_SPEED             = 0x0D;  // vehicle speed (km/h)
constexpr uint8_t PID_TIMING_ADVANCE    = 0x0E;  // timing advance (degrees BTDC)
constexpr uint8_t PID_INTAKE_TEMP       = 0x0F;  // intake air temperature (C)
constexpr uint8_t PID_MAF_RATE          = 0x10;  // MAF air flow rate (g/s)
constexpr uint8_t PID_THROTTLE          = 0x11;  // throttle position (%)
constexpr uint8_t PID_OBD_STANDARD      = 0x1C;  // OBD standards compliance
constexpr uint8_t PID_RUN_TIME          = 0x1F;  // run time since engine start (s)
constexpr uint8_t PID_SUPPORTED_21_40   = 0x20;  // supported PIDs [21-40]
constexpr uint8_t PID_FUEL_LEVEL        = 0x2F;  // fuel tank level input (%)
constexpr uint8_t PID_BARO_PRESSURE     = 0x33;  // barometric pressure (kPa)
constexpr uint8_t PID_SUPPORTED_41_60   = 0x40;  // supported PIDs [41-60]
constexpr uint8_t PID_CONTROL_VOLTAGE   = 0x42;  // control module voltage (V)
constexpr uint8_t PID_FUEL_TYPE         = 0x51;  // fuel type
constexpr uint8_t PID_OIL_TEMP          = 0x5C;  // engine oil temperature (C)
constexpr uint8_t PID_FUEL_RATE         = 0x5E;  // engine fuel rate (L/h)

// --- K-line protocol constants ---
constexpr uint8_t SYNC_BYTE             = 0x55;  // ECU sync response
constexpr uint8_t DEFAULT_TARGET        = 0x33;  // ISO 9141 default ECU address
constexpr uint8_t TESTER_ADDR           = 0xF1;  // external test equipment
constexpr uint8_t FUNC_ADDR             = 0x33;  // functional addressing

// --- ISO 14230 (KWP2000) header formats ---
constexpr uint8_t KWP_FMT_NO_ADDR      = 0x00;  // no address info
constexpr uint8_t KWP_FMT_PHYS_ADDR    = 0x80;  // physical addressing
constexpr uint8_t KWP_FMT_FUNC_ADDR    = 0xC0;  // functional addressing

// --- Decode helpers ---
// All formulas from SAE J1979 / ISO 15031-5

// PID 0x04: Calculated engine load (0-100%)
inline float decodeEngineLoad(uint8_t a) {
    return a * (100.0f / 255.0f);
}

// PID 0x05: Engine coolant temperature (-40 to 215 C)
inline int16_t decodeCoolantTemp(uint8_t a) {
    return (int16_t)a - 40;
}

// PID 0x06/0x07: Short/long term fuel trim (-100 to 99.2%)
inline float decodeFuelTrim(uint8_t a) {
    return (a / 1.28f) - 100.0f;
}

// PID 0x0B: Intake manifold pressure (0-255 kPa)
inline uint8_t decodeIntakePressure(uint8_t a) {
    return a;
}

// PID 0x0C: Engine RPM (0-16383.75 RPM) — 2 bytes
inline float decodeRpm(uint8_t a, uint8_t b) {
    return ((a * 256.0f) + b) / 4.0f;
}

// PID 0x0D: Vehicle speed (0-255 km/h)
inline uint8_t decodeSpeed(uint8_t a) {
    return a;
}

// PID 0x0E: Timing advance (-64 to 63.5 degrees BTDC)
inline float decodeTimingAdvance(uint8_t a) {
    return (a / 2.0f) - 64.0f;
}

// PID 0x0F: Intake air temperature (-40 to 215 C)
inline int16_t decodeIntakeTemp(uint8_t a) {
    return (int16_t)a - 40;
}

// PID 0x10: MAF air flow rate (0-655.35 g/s) — 2 bytes
inline float decodeMafRate(uint8_t a, uint8_t b) {
    return ((a * 256.0f) + b) / 100.0f;
}

// PID 0x11: Throttle position (0-100%)
inline float decodeThrottle(uint8_t a) {
    return a * (100.0f / 255.0f);
}

// PID 0x1F: Run time since engine start (0-65535 s) — 2 bytes
inline uint16_t decodeRunTime(uint8_t a, uint8_t b) {
    return (uint16_t)(a * 256) + b;
}

// PID 0x2F: Fuel tank level input (0-100%)
inline float decodeFuelLevel(uint8_t a) {
    return a * (100.0f / 255.0f);
}

// PID 0x33: Barometric pressure (0-255 kPa)
inline uint8_t decodeBaroPressure(uint8_t a) {
    return a;
}

// PID 0x42: Control module voltage (0-65.535 V) — 2 bytes
inline float decodeControlVoltage(uint8_t a, uint8_t b) {
    return ((a * 256.0f) + b) / 1000.0f;
}

// PID 0x5C: Engine oil temperature (-40 to 210 C)
inline int16_t decodeOilTemp(uint8_t a) {
    return (int16_t)a - 40;
}

// PID 0x5E: Engine fuel rate (0-3212.75 L/h) — 2 bytes
inline float decodeFuelRate(uint8_t a, uint8_t b) {
    return ((a * 256.0f) + b) / 20.0f;
}

}  // namespace obd2