#include "main/apic.h"
#include "main/io.h"
#include "util/printf.h"
#include "util/string.h"

/*
 * Debug message behavior.
 *
 * To disable a dbg mode add ',-name' to this variable. To enable one add
 * ',name'. For example to have everything except 'mm' and 'pagealloc' you would
 * set DBG to 'all,-mm,-pagealloc'. To have only 'test', 'testpass', 'testfail'
 * you would set DBG to '-all,test,testpass,testfail'.
 *
 * We generally recommend that you leave this set to 'all' with some of the
 * less useful message types disabled. To see all available message types, and
 * to potentially add to them see 'kernel/include/util/debug.h'
 *
 * Note that due to the way this is interpreted either 'all' or '-all' should
 * always be the first thing in this variable. Note that this setting can be
 * changed at runtime by modifying the dbg_modes global variable.
 */
#define INIT_DBG_MODES "-all,test,print,s5fs"

/* Below is a truly terrible poll-driven serial driver that we use for debugging
 * purposes - it outputs to COM1, but
 * this can be easily changed. It does not use interrupts, and cannot read input
 * */
/* This port is COM1 */
#define PORT 0x3f8
/* Corresponding interrupt vector */
#define PORT_INTR 0x0d

uint64_t dbg_modes;

typedef struct dbg_mode
{
    const char *d_name;
    uint64_t d_mode;
    const char *d_color;
} dbg_mode_t;

void dbg_init()
{
    outb(PORT + 3, 0x80); /* Enable DLAB (set baud rate divisor) */
    outb(PORT + 0, 0x03); /* Set divisor to 3 (lo byte) 38400 baud */
    outb(PORT + 1, 0x00); /*                  (hi byte) */
    outb(PORT + 3, 0x03); /* 8 bits, no parity, one stop bit */
    outb(PORT + 2, 0xC7); /* Enable FIFO, clear them, with 14-byte threshold */

    dbg_add_modes(INIT_DBG_MODES);
}

static dbg_mode_t dbg_tab[] = {DBG_TAB};

const char *dbg_color(uint64_t d_mode)
{
    dbg_mode_t *mode;
    for (mode = dbg_tab; mode->d_mode != 0UL; mode++)
    {
        if (mode->d_mode & d_mode)
        {
            return mode->d_color;
        }
    }
    /* If we get here, something went seriously wrong */
    panic("Unknown debug mode 0x%lx\n", d_mode);
}

static void dbg_puts(char *c)
{
    while (*c != '\0')
    {
        /* Wait until the port is free */
        while (!(inb(PORT + 5) & 0x20))
            ;
        outb(PORT, (uint8_t)*c++);
    }
}

#define BUFFER_SIZE 1024

void dbg_print(char *fmt, ...)
{
    va_list args;
    char buf[BUFFER_SIZE];
    size_t count;

    va_start(args, fmt);
    count = (size_t)vsnprintf(buf, sizeof(buf), fmt, args);
    va_end(args);

    if (count >= sizeof(buf))
    {
        dbg_puts(
            "WARNING: The following message has been truncated due to "
            "buffer size limitations.\n");
    }
    dbg_puts(buf);
}

void dbg_printinfo(dbg_infofunc_t func, const void *data)
{
    char buf[BUFFER_SIZE];
    func(data, buf, BUFFER_SIZE);
    dbg_puts(buf);
}

#ifndef NDEBUG
/**
 * searches for <code>name</code> in the list of known
 * debugging modes specified above and, if it
 * finds <code>name</code>, adds the corresponding
 * debugging mode to a list
 */
void dbg_add_mode(const char *name)
{
    long cancel;
    dbg_mode_t *mode;

    if (*name == '-')
    {
        cancel = 1;
        name++;
    }
    else
    {
        cancel = 0;
    }

    for (mode = dbg_tab; mode->d_name != NULL; mode++)
    {
        if (strcmp(name, mode->d_name) == 0)
        {
            break;
        }
    }
    if (mode->d_name == NULL)
    {
        dbg_print("Warning: Unknown debug option: \"%s\"\n", name);
        return;
    }

    if (cancel)
    {
        dbg_modes &= ~mode->d_mode;
    }
    else
    {
        dbg_modes |= mode->d_mode;
    }
}

/**
 * Cycles through each comma-delimited debugging option and
 * adds it to the debugging modes by calling dbg_add_mode
 */
void dbg_add_modes(const char *modes)
{
    char env[256];
    char *name;

    strncpy(env, modes, sizeof(env));
    /* Maybe it would be good if we did this without strtok, but I'm too lazy */
    for (name = strtok(env, ","); name; name = strtok(NULL, ","))
    {
        dbg_add_mode(name);
    }
}

size_t dbg_modes_info(const void *data, char *buf, size_t size)
{
    KASSERT(NULL == data);
    KASSERT(0 < size);

    size_t osize = size;

    dbg_mode_t *mode;
    for (mode = dbg_tab; mode->d_name != NULL; ++mode)
    {
        if (dbg_modes & mode->d_mode && mode->d_mode != DBG_ALL)
        {
            int len;
            if ((len = snprintf(buf, size, "%s,", mode->d_name)) >= (int)size)
            {
                break;
            }
            else
            {
                buf += len;
                size -= len;
            }
        }
    }

    if (size == osize)
    {
        buf[0] = '\0';
        return 0;
    }
    else
    {
        /* remove trailing comma */
        buf[-1] = '\0';
        return osize - size + 1;
    }
}
#endif

/* This is meant as a good point to automatically set a breakpoint which will
 * stop just after a panic has occured and printed its message. */
noreturn static void dbg_panic_halt()
{
    __asm__ volatile("cli; hlt");
    __builtin_unreachable();
}

#define PANIC_BUFSIZE 2048

noreturn void dbg_panic(const char *file, int line, const char *func,
                        const char *fmt, ...)
{
    char buf[PANIC_BUFSIZE];
    va_list args;
    va_start(args, fmt);

    DEBUG_ENTER
    dbg_print("C%ld P%ld panic in %s:%u %s(): ", curcore.kc_id,
              curproc ? curproc->p_pid : -1L, file, line, func);
    vsnprintf(buf, PANIC_BUFSIZE, fmt, args);
    dbg_print("%s", buf);
    dbg_print("\nC%ld Halting.\n\n", apic_current_id());
    DEBUG_EXIT

    va_end(args);

    dbg_panic_halt();
}