/*
 * Azeron Linux Configuration Library - Protocol Implementation
 * Copyright (C) 2024 Azeron Linux Project
 *
 * SPDX-License-Identifier: MIT
 */

#include "azeron.h"
#include "internal.h"
#include <string.h>
#include <unistd.h>
#include <stdio.h>

/* Configuration Interface Constants */
#define AZERON_CONFIG_ENDPOINT_OUT 0x06
#define AZERON_CONFIG_ENDPOINT_IN  0x85
#define AZERON_CONFIG_PACKET_SIZE  64

/* Command IDs */
#define AZERON_CMD_STATUS      0x122a
#define AZERON_CMD_READ_CONFIG 0x26FB
#define AZERON_CMD_WRITE_PROFILE 0x26EC
#define AZERON_CMD_SAVE_PROFILE  0x26ED

/* Cyborg Specific Surgical Commands */
#define AZERON_CMD_SET_SINGLE  0x20F6
#define AZERON_CMD_SET_LONG    0x20F8
#define AZERON_CMD_SET_DOUBLE  0x204A
#define AZERON_CMD_COMMIT_BTN  0x204B
#define AZERON_CMD_SET_GLOBAL  0x2000

/* Operation types */
#define AZERON_OP_READ_STATUS  0x0101
#define AZERON_OP_READ_CONFIG  0x0101
#define AZERON_OP_WRITE_PROFILE_0 0x0200
#define AZERON_OP_WRITE_PROFILE_1 0x0201
#define AZERON_OP_WRITE_PROFILE_2 0x0202
#define AZERON_OP_SAVE_PROFILE    0x0202

/* Offsets for profile data */
#define AZERON_PROFILE_BASE_OFFSET 0x0339
#define AZERON_BUTTON_MAPPING_SIZE 4
#define AZERON_STICK_CONFIG_OFFSET 58

/* Helper to dump hex data */
static void dump_hex(const char *label, const uint8_t *data, size_t len)
{
#ifdef AZERON_DEBUG
    fprintf(stderr, "[AZERON DEBUG] %s (%zu bytes):", label, len);
    for (size_t i = 0; i < len; i++) {
        fprintf(stderr, " %02x", data[i]);
    }
    fprintf(stderr, "\n");
#endif
}

/* Build a standard 64-byte configuration packet */
static int build_config_packet(uint8_t *packet, uint16_t command, uint16_t operation,
                             const uint8_t *data, size_t data_len)
{
    if (!packet || data_len > 58) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    /* Clear packet */
    memset(packet, 0, AZERON_CONFIG_PACKET_SIZE);

    /* Build header */
    packet[0] = 0x00; /* Request packet */
    packet[1] = 0x3a; /* Payload length (fixed 58 bytes for config) */
    packet[2] = (command >> 8) & 0xFF; /* Command ID high byte */
    packet[3] = command & 0xFF;        /* Command ID low byte */
    packet[4] = (operation >> 8) & 0xFF; /* Operation high byte */
    packet[5] = operation & 0xFF;        /* Operation low byte */

    /* Copy data payload if provided */
    if (data && data_len > 0) {
        memcpy(&packet[6], data, data_len);
    }

    return AZERON_SUCCESS;
}

/* Send a configuration command and wait for response */
static int send_config_command(struct azeron_device *device, uint16_t command, uint16_t operation,
                             const uint8_t *request_data, size_t request_len,
                             uint8_t *response, size_t *response_len)
{
    uint8_t request_packet[AZERON_CONFIG_PACKET_SIZE];
    uint8_t response_packet[AZERON_CONFIG_PACKET_SIZE];
    int ret;

    if (!device || !response || !response_len) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    /* Build request packet */
    ret = build_config_packet(request_packet, command, operation, request_data, request_len);
    if (ret != AZERON_SUCCESS) {
        return ret;
    }

    dump_hex("Request", request_packet, AZERON_CONFIG_PACKET_SIZE);

    /* Send request */
    ret = azeron_device_write(device, AZERON_CONFIG_ENDPOINT_OUT,
                            request_packet, AZERON_CONFIG_PACKET_SIZE, AZERON_USB_TIMEOUT);
    if (ret < 0) {
        AZERON_ERROR("Failed to send command 0x%04x: %s", command, azeron_error_string(ret));
        return ret;
    }

    /* Wait for device to process - configuration read might take longer */
    usleep(50000); /* 50ms */

    /* Read response */
    ret = azeron_device_read(device, AZERON_CONFIG_ENDPOINT_IN,
                           response_packet, AZERON_CONFIG_PACKET_SIZE, AZERON_USB_TIMEOUT);
    if (ret < 0) {
        AZERON_ERROR("Failed to read response for command 0x%04x: %s", command, azeron_error_string(ret));
        return ret;
    }

    dump_hex("Response", response_packet, AZERON_CONFIG_PACKET_SIZE);

    /* Validate response */
    if (ret != AZERON_CONFIG_PACKET_SIZE) {
        AZERON_ERROR("Invalid response size: %d (expected %d)", ret, AZERON_CONFIG_PACKET_SIZE);
        return AZERON_ERROR_PROTOCOL;
    }

    /* Check response type */
    if (response_packet[0] != 0x01 && response_packet[0] != 0x00) {
        AZERON_ERROR("Invalid response type: 0x%02x", response_packet[0]);
        return AZERON_ERROR_PROTOCOL;
    }

    /* Check command ID matches */
    uint16_t response_command = (response_packet[2] << 8) | response_packet[3];
    if (response_command != command) {
        AZERON_ERROR("Command mismatch: sent 0x%04x, got 0x%04x", command, response_command);
        return AZERON_ERROR_PROTOCOL;
    }

    /* Check status - Byte 6 seems to be 0x01 for success in most responses */
    if (response_packet[6] != 0x01 && response_packet[6] != 0x00) {
        AZERON_ERROR("Command failed with status: 0x%02x", response_packet[6]);
        return AZERON_ERROR_PROTOCOL;
    }

    /* Copy response data (skip 6-byte header) */
    *response_len = ret - 6;
    if (*response_len > 0) {
        memcpy(response, &response_packet[6], *response_len);
    }

    AZERON_LOG("Command 0x%04x completed successfully", command);
    return AZERON_SUCCESS;
}

/* Protocol initialization */
int azeron_protocol_init(struct azeron_device *device)
{
    uint8_t response[64];
    size_t response_len;
    int ret;

    if (!device) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    /* Send status command to verify communication */
    ret = send_config_command(device, AZERON_CMD_STATUS, AZERON_OP_READ_STATUS,
                            NULL, 0, response, &response_len);
    if (ret != AZERON_SUCCESS) {
        AZERON_ERROR("Failed to initialize protocol: %s", azeron_error_string(ret));
        return ret;
    }

    AZERON_LOG("Protocol initialized successfully");
    return AZERON_SUCCESS;
}

/* Read configuration from device at specific offset */
int azeron_protocol_read_config(struct azeron_device *device, uint32_t offset, uint8_t *data, size_t *size)
{
    uint8_t response[64];
    size_t response_len;
    uint8_t request_data[58] = {0};
    int ret;

    if (!device || !data || !size) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    /* Set offset in request (LITTLE ENDIAN) */
    request_data[0] = offset & 0xFF;
    request_data[1] = (offset >> 8) & 0xFF;
    request_data[2] = (offset >> 16) & 0xFF;
    request_data[3] = (offset >> 24) & 0xFF;

    ret = send_config_command(device, AZERON_CMD_READ_CONFIG, AZERON_OP_READ_CONFIG,
                            request_data, 4, response, &response_len);
    if (ret != AZERON_SUCCESS) {
        return ret;
    }

    if (response_len > *size) {
        response_len = *size;
    }

    memcpy(data, response, response_len);
    *size = response_len;

    return AZERON_SUCCESS;
}

/* Write configuration to device */
int azeron_protocol_write_config(struct azeron_device *device, const uint8_t *data, size_t size)
{
    (void)device;
    (void)data;
    (void)size;
    AZERON_LOG("Write config - not yet implemented");
    return AZERON_ERROR_UNSUPPORTED;
}

/* Get button mapping */
int azeron_protocol_get_button_mapping(struct azeron_device *device, uint8_t button_id,
                                     struct azeron_button_mapping *mapping)
{
    uint8_t response[64];
    size_t response_len;
    int ret;

    if (!device || !mapping) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    if (button_id >= AZERON_MAX_BUTTONS) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    /* Status command returns the full profile block in Cyborg */
    ret = send_config_command(device, AZERON_CMD_STATUS, AZERON_OP_READ_STATUS,
                            NULL, 0, response, &response_len);
    if (ret != AZERON_SUCCESS) {
        return ret;
    }

    /* 
     * response[0] is status
     * response[1..58] is profile data.
     * Mappings start at profile index 8 (response[9]).
     * Each button has 3 actions, 4 bytes each = 12 bytes per button.
     */
    uint32_t profile_idx = 8 + (button_id * 3 * 4) + (mapping->action * 4);
    
    /* Mapping structure: [Type, Code, 0, 0] */
    uint8_t type_byte = response[profile_idx + 1];
    mapping->key_code = response[profile_idx + 2];
    mapping->button_id = button_id;
    
    switch (type_byte) {
    case 0xf0: mapping->type = AZERON_BTN_KEYBOARD; break;
    case 0xf1: mapping->type = AZERON_BTN_MOUSE; break;
    case 0xf2: mapping->type = AZERON_BTN_GAMEPAD; break;
    default:   mapping->type = AZERON_BTN_KEYBOARD; break;
    }

    mapping->macro = NULL;
    mapping->layer_target = 0;

    return AZERON_SUCCESS;
}

/* Set button mapping */
int azeron_protocol_set_button_mapping(struct azeron_device *device,
                                     const struct azeron_button_mapping *mapping)
{
    uint8_t response[64];
    size_t response_len;
    uint8_t data[58] = {0};
    uint16_t command;
    int ret;

    if (!device || !mapping) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    /* Select surgical command based on action type */
    switch (mapping->action) {
    case AZERON_ACTION_SINGLE: command = AZERON_CMD_SET_SINGLE; break;
    case AZERON_ACTION_LONG:   command = AZERON_CMD_SET_LONG;   break;
    case AZERON_ACTION_DOUBLE: command = AZERON_CMD_SET_DOUBLE; break;
    default: return AZERON_ERROR_INVALID_PARAM;
    }

    /* Surgical payload structure for Cyborg:
     * Byte 4: 0x01 (fixed?)
     * Byte 5: 0x01 (fixed?)
     * Byte 10: Button ID
     * Byte 11: Sub-action index? (usually 0x01 or 0x02)
     * Byte 22: Key Type
     * Byte 23: Key Code
     */
    
    data[4] = 0x01;
    data[10] = mapping->button_id;
    
    switch (mapping->action) {
    case AZERON_ACTION_SINGLE: data[11] = 0x01; break;
    case AZERON_ACTION_LONG:   data[11] = 0x00; break; /* As seen in capture */
    case AZERON_ACTION_DOUBLE: data[11] = 0x00; break; /* As seen in capture */
    }

    switch (mapping->type) {
    case AZERON_BTN_KEYBOARD: data[22] = 0xf0; break;
    case AZERON_BTN_MOUSE:    data[22] = 0xf1; break;
    case AZERON_BTN_GAMEPAD:  data[22] = 0xf2; break;
    default: return AZERON_ERROR_UNSUPPORTED;
    }
    
    data[23] = mapping->key_code & 0xFF;

    ret = send_config_command(device, command, 0x0101,
                            data, 24, response, &response_len);
    
    if (ret == AZERON_SUCCESS) {
        /* Follow up with commitment command to make it live */
        ret = send_config_command(device, AZERON_CMD_COMMIT_BTN, 0x0101,
                                NULL, 0, response, &response_len);
    }
    
    return ret;
}

/* Get stick configuration */
int azeron_protocol_get_stick_config(struct azeron_device *device,
                                   struct azeron_stick_config *config)
{
    uint8_t response[64];
    size_t response_len;
    int ret;

    if (!device || !config) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    /* Status command returns the full profile block in Cyborg */
    ret = send_config_command(device, AZERON_CMD_STATUS, AZERON_OP_READ_STATUS,
                            NULL, 0, response, &response_len);
    if (ret != AZERON_SUCCESS) {
        return ret;
    }

    /* 
     * response[0] is status (usually 0x01)
     * response[1..58] is the profile payload data.
     * Index 3 in payload is response[4].
     */
    config->mode = (enum azeron_stick_mode)response[4];
    config->angle = response[9]; /* index 8 in payload */
    config->deadzone = response[11]; /* index 10 */
    config->response_curve = response[12]; /* index 11 */
    config->sensitivity = response[13]; /* index 12 */
    config->invert_x = response[14] & 0x01; /* index 13 */
    config->invert_y = (response[14] >> 1) & 0x01;

    return AZERON_SUCCESS;
}

/* Set stick configuration */
int azeron_protocol_set_stick_config(struct azeron_device *device,
                                   const struct azeron_stick_config *config)
{
    uint8_t response[64];
    size_t response_len;
    uint8_t data[58] = {0};
    uint16_t operation;
    uint8_t active_profile;
    int ret;

    if (!device || !config) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    /* Get active profile */
    ret = azeron_protocol_get_active_profile(device, &active_profile);
    if (ret != AZERON_SUCCESS) {
        return ret;
    }

    /* Operation selects which profile slot to write to */
    switch (active_profile) {
    case 0: operation = AZERON_OP_WRITE_PROFILE_0; break;
    case 1: operation = AZERON_OP_WRITE_PROFILE_1; break;
    case 2: operation = AZERON_OP_WRITE_PROFILE_2; break;
    default: return AZERON_ERROR_PROTOCOL;
    }

    /* Cyborg Bulk Write Format for 0x26EC:
     * Index 0-1: Base offset (0x39 0x03)
     * Index 3: Mode
     * Index 8: Angle
     * Index 10: Deadzone
     */
    data[0] = AZERON_PROFILE_BASE_OFFSET & 0xFF;
    data[1] = (AZERON_PROFILE_BASE_OFFSET >> 8) & 0xFF;
    data[3] = (uint8_t)config->mode;
    data[8] = config->angle;
    data[10] = config->deadzone;

    ret = send_config_command(device, AZERON_CMD_WRITE_PROFILE, operation,
                            data, 58, response, &response_len);
    
    return ret;
}

/* Set global timings */
int azeron_protocol_set_global_timings(struct azeron_device *device, uint16_t long_press_delay, uint16_t double_click_delay)
{
    uint8_t response[64];
    size_t response_len;
    uint8_t data[58] = {0};
    int ret;

    if (!device) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    /* Delay values are LITTLE ENDIAN at the very end of the 58-byte payload */
    data[54] = long_press_delay & 0xFF;
    data[55] = (long_press_delay >> 8) & 0xFF;
    data[56] = double_click_delay & 0xFF;
    data[57] = (double_click_delay >> 8) & 0xFF;

    ret = send_config_command(device, AZERON_CMD_SET_GLOBAL, 0x0101,
                            data, 58, response, &response_len);
    
    return ret;
}

/* Get active profile */
int azeron_protocol_get_active_profile(struct azeron_device *device, uint8_t *profile_id)
{
    uint8_t response[64];
    size_t response_len;
    int ret;

    if (!device || !profile_id) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    ret = send_config_command(device, AZERON_CMD_STATUS, AZERON_OP_READ_STATUS,
                            NULL, 0, response, &response_len);
    if (ret != AZERON_SUCCESS) {
        return ret;
    }

    /* Byte 1 of payload data (skipping 6-byte header) is profile ID */
    *profile_id = response[1];

    AZERON_LOG("Active profile: %d", *profile_id);
    return AZERON_SUCCESS;
}

/* Set active profile */
int azeron_protocol_set_active_profile(struct azeron_device *device, uint8_t profile_id)
{
    return azeron_protocol_save_to_device(device, profile_id);
}

/* Get profile */
int azeron_protocol_get_profile(struct azeron_device *device, uint8_t profile_id,
                              struct azeron_profile *profile)
{
    (void)device;
    (void)profile_id;
    (void)profile;
    return AZERON_ERROR_UNSUPPORTED;
}

/* Set profile */
int azeron_protocol_set_profile(struct azeron_device *device,
                              const struct azeron_profile *profile)
{
    (void)device;
    (void)profile;
    return AZERON_ERROR_UNSUPPORTED;
}

/* Save configuration to device */
int azeron_protocol_save_to_device(struct azeron_device *device, uint8_t profile_id)
{
    uint8_t response[64];
    size_t response_len;
    int ret;

    if (device == NULL) {
        return AZERON_ERROR_INVALID_PARAM;
    }

    if (profile_id > 2) {
        AZERON_ERROR("Invalid profile ID: %d (must be 0, 1 or 2)", profile_id);
        return AZERON_ERROR_INVALID_PARAM;
    }

    uint8_t save_data[58] = {0};
    save_data[0] = profile_id;
    
    ret = send_config_command(device, AZERON_CMD_SAVE_PROFILE, AZERON_OP_SAVE_PROFILE,
                            save_data, 1, response, &response_len);
    
    return ret;
}