/* Pactor64 — Raspberry Pi 5 Kernel Main (AArch64) */
#include "uart.h"

#define CMD_BUF_SIZE 128

static int kstrcmp(const char *a, const char *b) {
    while (*a && *a == *b) { a++; b++; }
    return (unsigned char)*a - (unsigned char)*b;
}

static void kprintf(const char *fmt, ...) {
    __builtin_va_list ap;
    __builtin_va_start(ap, fmt);
    for (int i = 0; fmt[i]; i++) {
        if (fmt[i] == '%' && fmt[i+1]) {
            i++;
            switch (fmt[i]) {
                case 'd': {
                    long v = __builtin_va_arg(ap, long);
                    if (v < 0) { uart_putc('-'); v = -v; }
                    char b[21]; int j = 0;
                    if (v == 0) { uart_putc('0'); break; }
                    while (v > 0) { b[j++] = '0' + (v % 10); v /= 10; }
                    while (j > 0) uart_putc(b[--j]);
                    break;
                }
                case 's': {
                    const char *s = __builtin_va_arg(ap, const char *);
                    uart_puts(s ? s : "(null)");
                    break;
                }
                case '%': uart_putc('%'); break;
                default: uart_putc('%'); uart_putc(fmt[i]); break;
            }
        } else {
            uart_putc(fmt[i]);
        }
    }
    __builtin_va_end(ap);
}

static void cmd_help(void) {
    uart_puts("  Available commands:\r\n");
    uart_puts("    help    - Show this help\r\n");
    uart_puts("    sysinfo - System information\r\n");
    uart_puts("    halt    - Halt the system\r\n");
}

static void cmd_sysinfo(void) {
    uart_puts("  ================================\r\n");
    uart_puts("  Pactor64 System Information\r\n");
    uart_puts("  ================================\r\n");
    uart_puts("  Architecture:  AArch64 (ARMv8.2-A)\r\n");
    uart_puts("  CPU:           Cortex-A76\r\n");
    uart_puts("  Board:         Raspberry Pi 5\r\n");
    uart_puts("  SoC:           BCM2712\r\n");
    uart_puts("  Console:       PL011 UART @ 115200 baud\r\n");
    uart_puts("  ================================\r\n");
}

static void execute_command(const char *cmd) {
    while (*cmd == ' ') cmd++;
    if (*cmd == '\0') return;
    if (kstrcmp(cmd, "help") == 0) cmd_help();
    else if (kstrcmp(cmd, "sysinfo") == 0) cmd_sysinfo();
    else if (kstrcmp(cmd, "halt") == 0) {
        uart_puts("  System halted.\r\n");
        for (;;) __asm__ volatile("wfe");
    } else {
        kprintf("  Unknown: '%s'\r\n", cmd);
    }
}

static void shell_run(void) {
    char buf[CMD_BUF_SIZE];
    int pos = 0;
    uart_puts("pactor64> ");
    for (;;) {
        int c = uart_getc();
        if (c < 0) continue;
        char ch = (char)c;
        if (ch == '\r' || ch == '\n') {
            uart_puts("\r\n");
            buf[pos] = '\0';
            execute_command(buf);
            pos = 0;
            uart_puts("pactor64> ");
        } else if (ch == 0x7F || ch == '\b') {
            if (pos > 0) { pos--; uart_puts("\b \b"); }
        } else if (pos < CMD_BUF_SIZE - 1) {
            buf[pos++] = ch;
            uart_putc(ch);
        }
    }
}

void kernel_main(void) {
    uart_puts("\r\n");
    uart_puts("  ================================\r\n");
    uart_puts("  Pactor64 on Raspberry Pi 5\r\n");
    uart_puts("  Cortex A76 (AArch64)\r\n");
    uart_puts("  ================================\r\n");
    uart_puts("\r\n  [OK] Kernel initialized\r\n");
    uart_puts("  [OK] UART console ready\r\n");
    uart_puts("\r\n  Type 'help' for available commands.\r\n\r\n");
    shell_run();
}