#pragma once

#include <array>
#include <cstddef>
#include <cstdint>
#include <span>

// ==============================================================================
// Standard Xbox One HID report layout
// ==============================================================================
// The virtual gamepad presents the standard Xbox One controller report
// layout so games that expect an Xbox controller (raw HID or via the
// GameController framework) recognize it natively.
//
// Input report (ID 1, 64 bytes):
//   [0]      report ID
//   [1..2]   buttons, little-endian u16:
//            A,B,X,Y,LB,RB,LS,RS,Back,Start,DpadU,DpadD,DpadL,DpadR
//   [3]      guide button (0/1)
//   [4]      left trigger  (8-bit, HID usage Z)
//   [5]      right trigger (8-bit, HID usage Rz)
//   [6..7]   left stick X  (s16 LE, usage X)
//   [8..9]   left stick Y  (s16 LE, usage Y)
//   [10..11] right stick X (s16 LE, usage Rx)
//   [12..13] right stick Y (s16 LE, usage Ry)
//   [14..63] reserved (zero)
//
// Output report (ID 1, 64 bytes):
//   [0]      report ID
//   [1]      reserved
//   [2]      left motor intensity (8-bit)
//   [3]      right motor intensity (8-bit)
//   [4..63]  reserved (zero)
// ==============================================================================

namespace xone::hid {

constexpr std::uint8_t k_report_id = 1;
constexpr std::size_t k_input_report_size = 64;
constexpr std::size_t k_output_report_size = 64;

// Offsets within the input report.
constexpr std::size_t k_in_buttons = 1;      // u16 LE
constexpr std::size_t k_in_guide = 3;
constexpr std::size_t k_in_trigger_left = 4;
constexpr std::size_t k_in_trigger_right = 5;
constexpr std::size_t k_in_stick_left_x = 6;   // s16 LE
constexpr std::size_t k_in_stick_left_y = 8;
constexpr std::size_t k_in_stick_right_x = 10;
constexpr std::size_t k_in_stick_right_y = 12;

// Offsets within the output report.
constexpr std::size_t k_out_motor_left = 2;
constexpr std::size_t k_out_motor_right = 3;

// HID report descriptor matching the layout above (input + output).
auto xbox_one_report_descriptor() -> std::span<std::uint8_t const>;

// Normalized controller input, as tracked from GIP events. Stick Y is
// already oriented so up is positive; triggers are 10-bit values (0..1023)
// in the low bits of the u16. Buttons use the GIP bitmask (A=bit4 ...
// RS=bit15, Start=bit2, Select=bit3).
struct gamepad_input {
    std::uint16_t buttons = 0;
    bool guide_down = false;
    std::uint16_t trigger_left = 0;
    std::uint16_t trigger_right = 0;
    std::int16_t stick_left_x = 0;
    std::int16_t stick_left_y = 0;
    std::int16_t stick_right_x = 0;
    std::int16_t stick_right_y = 0;
};

// Build a standard Xbox One input report from normalized GIP state.
auto make_input_report(gamepad_input const& in)
    -> std::array<std::uint8_t, k_input_report_size>;

// Motor intensities parsed from an output report (0..255 each).
struct motor_values {
    std::uint8_t left = 0;
    std::uint8_t right = 0;
};

// Parse a standard Xbox One output report. Returns zeroed motors (which
// stops the rumble) if the report ID or size does not match.
auto parse_output_report(std::span<std::uint8_t const> report)
    -> motor_values;

} // namespace xone::hid