#include <stddef.h>
#include <stdbool.h>
#include <lib/config.h>
#include <lib/libc.h>
#include <lib/blib.h>
#include <mm/pmm.h>
#include <fs/file.h>
#include <lib/print.h>
#include <pxe/tftp.h>

#include <sys/cpu.h>

#define SEPARATOR '\n'

bool config_ready = false;

static char *config_addr;

int init_config_disk(struct volume *part) {
    struct file_handle f;

    if (fopen(&f, part, "/limine.cfg")
     && fopen(&f, part, "/boot/limine.cfg")
     && fopen(&f, part, "/EFI/BOOT/limine.cfg")) {
        return -1;
    }

    size_t config_size = f.size + 1;
    config_addr = ext_mem_alloc(config_size);

    fread(&f, config_addr, 0, f.size);

    return init_config(config_size);
}

#if defined (bios)
int init_config_pxe(void) {
    struct tftp_file_handle cfg;
    if (tftp_open(&cfg, 0, 69, "limine.cfg")) {
        return -1;
    }
    config_addr = ext_mem_alloc(cfg.file_size);
    tftp_read(&cfg, config_addr, 0, cfg.file_size);

    return init_config(cfg.file_size);
}
#endif

#define NOT_CHILD      (-1)
#define DIRECT_CHILD   0
#define INDIRECT_CHILD 1

static int is_child(char *buf, size_t limit,
                    size_t current_depth, size_t index) {
    if (!config_get_entry_name(buf, index, limit))
        return NOT_CHILD;
    if (strlen(buf) < current_depth + 1)
        return NOT_CHILD;
    for (size_t j = 0; j < current_depth; j++)
        if (buf[j] != ':')
            return NOT_CHILD;
    if (buf[current_depth] == ':')
        return INDIRECT_CHILD;
    return DIRECT_CHILD;
}

static bool is_directory(char *buf, size_t limit,
                         size_t current_depth, size_t index) {
    switch (is_child(buf, limit, current_depth + 1, index + 1)) {
        default:
        case NOT_CHILD:
            return false;
        case INDIRECT_CHILD:
            panic("config: Malformed config file. Parentless child.");
        case DIRECT_CHILD:
            return true;
    }
}

static struct menu_entry *create_menu_tree(struct menu_entry *parent,
                                           size_t current_depth, size_t index) {
    struct menu_entry *root = NULL, *prev = NULL;

    for (size_t i = index; ; i++) {
        static char name[64];

        switch (is_child(name, 64, current_depth, i)) {
            case NOT_CHILD:
                return root;
            case INDIRECT_CHILD:
                continue;
            case DIRECT_CHILD:
                break;
        }

        struct menu_entry *entry = ext_mem_alloc(sizeof(struct menu_entry));

        if (root == NULL)
            root = entry;

        config_get_entry_name(name, i, 64);

        bool default_expanded = name[current_depth] == '+';

        strcpy(entry->name, name + current_depth + default_expanded);
        entry->parent = parent;

        if (is_directory(name, 64, current_depth, i)) {
            entry->sub = create_menu_tree(entry, current_depth + 1, i + 1);
            entry->expanded = default_expanded;
        } else {
            size_t entry_size;
            char *config_entry = config_get_entry(&entry_size, i);
            entry->body = ext_mem_alloc(entry_size + 1);
            memcpy(entry->body, config_entry, entry_size);
            entry->body[entry_size] = 0;
        }

        if (prev != NULL)
            prev->next = entry;
        prev = entry;
    }
}

struct menu_entry *menu_tree = NULL;

int init_config(size_t config_size) {
    // remove windows carriage returns, if any
    for (size_t i = 0; i < config_size; i++) {
        if (config_addr[i] == '\r') {
            for (size_t j = i; j < config_size - 1; j++)
                config_addr[j] = config_addr[j+1];
            config_size--;
        }
    }

    config_ready = true;

    menu_tree = create_menu_tree(NULL, 1, 0);

    return 0;
}

bool config_get_entry_name(char *ret, size_t index, size_t limit) {
    if (!config_ready)
        return false;

    char *p = config_addr;

    for (size_t i = 0; i <= index; i++) {
        while (*p != ':') {
            if (!*p)
                return false;
            p++;
        }
        p++;
        if ((p - 1) != config_addr && *(p - 2) != '\n')
            i--;
    }

    p--;

    size_t i;
    for (i = 0; i < (limit - 1); i++) {
        if (p[i] == SEPARATOR)
            break;
        ret[i] = p[i];
    }

    ret[i] = 0;
    return true;
}

char *config_get_entry(size_t *size, size_t index) {
    if (!config_ready)
        return NULL;

    char *ret;
    char *p = config_addr;

    for (size_t i = 0; i <= index; i++) {
        while (*p != ':') {
            if (!*p)
                return NULL;
            p++;
        }
        p++;
        if ((p - 1) != config_addr && *(p - 2) != '\n')
            i--;
    }

    do {
        p++;
    } while (*p != '\n');

    ret = p;

cont:
    while (*p != ':' && *p)
        p++;

    if (*p && *(p - 1) != '\n') {
        p++;
        goto cont;
    }

    *size = p - ret;

    return ret;
}

char *config_get_value(const char *config, size_t index, const char *key) {
    if (!key || !config_ready)
        return NULL;

    if (config == NULL)
        config = config_addr;

    size_t key_len = strlen(key);

    for (size_t i = 0; config[i]; i++) {
        if (!strncmp(&config[i], key, key_len) && config[i + key_len] == '=') {
            if (i && config[i - 1] != SEPARATOR)
                continue;
            if (index--)
                continue;
            i += key_len + 1;
            size_t value_len;
            for (value_len = 0;
                 config[i + value_len] != SEPARATOR && config[i + value_len];
                 value_len++);
            char *buf = ext_mem_alloc(value_len + 1);
            memcpy(buf, config + i, value_len);
            return buf;
        }
    }

    return NULL;
}