#include "uart.h"
#include "stdio.h"
#include "abi/syscalls.h"
#include "abi/ipc.h"

#define UART_SERVICE_ENDPOINT 2

extern void _start(void) {
    uart_init(UART_COM1_PORT, 115200);
    puts("[UART-DRIVER] 16550 UART Server started in Ring 3. Listening for IPC requests...");

    uint64_t last_client = 0;
    uint64_t reply_val0 = 0;
    uint64_t reply_val1 = 0;

    while (1) {
        uint64_t sender_tid = 0;
        uint64_t opcode = 0;
        uint64_t arg0 = 0;
        uint64_t arg1 = 0;

        // Block and wait for next client IPC request, replying to last client if any
        sysret_t ret = sys_ipc_reply_recv_raw(
            UART_SERVICE_ENDPOINT,
            last_client,
            reply_val0,
            reply_val1,
            &sender_tid,
            &opcode,
            &arg0,
            &arg1
        );

        if (ret == 0 && sender_tid != 0) {
            last_client = sender_tid;

            if (opcode == IPC_OP_WRITE) {
                // Write received characters to UART hardware
                char c0 = (char)(arg0 & 0xFF);
                char c1 = (char)((arg0 >> 8) & 0xFF);
                char c2 = (char)((arg0 >> 16) & 0xFF);
                char c3 = (char)((arg0 >> 24) & 0xFF);

                if (c0) uart_putc(UART_COM1_PORT, c0);
                if (c1) uart_putc(UART_COM1_PORT, c1);
                if (c2) uart_putc(UART_COM1_PORT, c2);
                if (c3) uart_putc(UART_COM1_PORT, c3);

                reply_val0 = 0; // Success
                reply_val1 = 4; // Bytes written
            } else if (opcode == IPC_OP_PING) {
                reply_val0 = IPC_OP_PONG;
                reply_val1 = arg0 + 1;
            } else {
                reply_val0 = (uint64_t)-1;
                reply_val1 = 0;
            }
        } else {
            last_client = 0;
            sys_yield();
        }
    }
}