#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>

#include "eip712.h"
#include "mem.h"


static uint8_t  *typenames_array;
static uint8_t  *structs_array;
static uint8_t  *current_struct_fields_array;

// lib functions
const void *get_array_in_mem(const void *ptr, uint8_t *const array_size)
{
    *array_size = *(uint8_t*)ptr;
    return (ptr + 1);
}

static inline const char *get_string_in_mem(const uint8_t *ptr, uint8_t *const string_length)
{
    return (char*)get_array_in_mem(ptr, string_length);
}

// ptr must point to the beginning of a struct field
static inline uint8_t get_struct_field_typedesc(const uint8_t *ptr)
{
    return *ptr;
}

// ptr must point to the beginning of a struct field
static inline bool    struct_field_is_array(const uint8_t *ptr)
{
    return (get_struct_field_typedesc(ptr) & ARRAY_MASK);
}

// ptr must point to the beginning of a struct field
static inline bool    struct_field_has_typesize(const uint8_t *ptr)
{
    return (get_struct_field_typedesc(ptr) & TYPESIZE_MASK);
}

// ptr must point to the beginning of a struct field
static inline e_type  struct_field_type(const uint8_t *ptr)
{
    return (get_struct_field_typedesc(ptr) & TYPE_MASK);
}

// ptr must point to the beginning of a struct field
// TODO: Extra check inside or not
uint8_t get_struct_field_typesize(const uint8_t *ptr)
{
    return *(ptr + 1);
}

// ptr must point to the beginning of a struct field
const char *get_struct_field_custom_typename(const uint8_t *ptr,
                                                uint8_t *const length)
{
    ptr += 1; // skip TypeDesc
    return get_string_in_mem(ptr, length);
}

// ptr must point to the beginning of a struct field
const char *get_struct_field_sol_typename(const uint8_t *ptr,
                                             uint8_t *const length)
{
    e_type field_type;
    const uint8_t *typename_ptr;
    uint8_t typenames_count;
    bool more_type;
    bool typename_found;

    field_type = struct_field_type(ptr);
    typename_ptr = get_array_in_mem(typenames_array, &typenames_count);
    typename_found = false;
    while (typenames_count-- > 0)
    {
        more_type = true;
        while (more_type)
        {
            more_type = *typename_ptr & TYPENAME_MORE_TYPE;
            e_type type_enum = *typename_ptr & TYPENAME_ENUM;
            if (type_enum == field_type)
            {
                typename_found = true;
            }
            typename_ptr += 1;
        }
        typename_ptr = (uint8_t*)get_string_in_mem(typename_ptr, length);
        if (typename_found) return (char*)typename_ptr;
        typename_ptr += *length;
    }
    return NULL; // Not found
}

// ptr must point to the beginning of a struct field
const char *get_struct_field_typename(const uint8_t *ptr,
                                         uint8_t *const length)
{
    if (struct_field_type(ptr) == TYPE_CUSTOM)
    {
        return get_struct_field_custom_typename(ptr, length);
    }
    return get_struct_field_sol_typename(ptr, length);
}

// ptr must point to the beginning of a depth level
e_array_type struct_field_array_depth(const uint8_t *ptr,
                                      uint8_t *const array_size)
{
    if (*ptr == ARRAY_FIXED_SIZE)
    {
        *array_size = *(ptr + 1);
    }
    return *ptr;
}

// ptr must point to the beginning of a struct field level
const uint8_t *get_next_struct_field_array_lvl(const uint8_t *ptr)
{
    switch (*ptr)
    {
        case ARRAY_DYNAMIC:
            break;
        case ARRAY_FIXED_SIZE:
            ptr += 1;
            break;
        default:
            // should not be in here :^)
            break;
    }
    return ptr + 1;
}

// Skips TypeDesc and TypeSize/Length+TypeName
// Came to be since it is used in multiple functions
// TODO: Find better name
const uint8_t *struct_field_half_skip(const uint8_t *ptr)
{
    const uint8_t *field_ptr;
    uint8_t size;

    field_ptr = ptr;
    ptr += 1; // skip TypeDesc
    if (struct_field_type(field_ptr) == TYPE_CUSTOM)
    {
        get_string_in_mem(ptr, &size);
        ptr += (1 + size); // skip typename
    }
    else if (struct_field_has_typesize(field_ptr))
    {
        ptr += 1; // skip TypeSize
    }
    return ptr;
}

// ptr must point to the beginning of a struct field
const uint8_t *get_struct_field_array_lvls_array(const uint8_t *ptr,
                                                 uint8_t *const length)
{
    ptr = struct_field_half_skip(ptr);
    return get_array_in_mem(ptr, length);
}

// ptr must point to the beginning of a struct field
const char *get_struct_field_keyname(const uint8_t *ptr,
                                        uint8_t *const length)
{
    const uint8_t *field_ptr;
    uint8_t size;

    field_ptr = ptr;
    ptr = struct_field_half_skip(ptr);
    if (struct_field_is_array(field_ptr))
    {
        ptr = get_array_in_mem(ptr, &size);
        while (size-- > 0)
        {
            ptr = get_next_struct_field_array_lvl(ptr);
        }
    }
    return get_string_in_mem(ptr, length);
}

// ptr must point to the beginning of a struct field
const uint8_t *get_next_struct_field(const void *ptr)
{
    uint8_t length;

    ptr = (uint8_t*)get_struct_field_keyname(ptr, &length);
    return (ptr + length);
}

// ptr must point to the beginning of a struct
const char *get_struct_name(const uint8_t *ptr, uint8_t *const length)
{
    return (char*)get_string_in_mem(ptr, length);
}

// ptr must point to the beginning of a struct
const uint8_t *get_struct_fields_array(const uint8_t *ptr,
                                       uint8_t *const length)
{
    uint8_t name_length;

    get_struct_name(ptr, &name_length);
    ptr += (1 + name_length); // skip length
    return get_array_in_mem(ptr, length);
}

// ptr must point to the beginning of a struct
const uint8_t *get_next_struct(const uint8_t *ptr)
{
    uint8_t fields_count;

    ptr = get_struct_fields_array(ptr, &fields_count);
    while (fields_count-- > 0)
    {
        ptr = get_next_struct_field(ptr);
    }
    return ptr;
}

// ptr must point to the size of the structs array
const uint8_t *get_structs_array(const uint8_t *ptr, uint8_t *const length)
{
    return get_array_in_mem(ptr, length);
}

// Finds struct with a given name
const uint8_t *get_structn(const uint8_t *const ptr,
                           const char *const name_ptr,
                           const uint8_t name_length)
{
    uint8_t structs_count;
    const uint8_t *struct_ptr;
    const char *name;
    uint8_t length;

    struct_ptr = get_structs_array(ptr, &structs_count);
    while (structs_count-- > 0)
    {
        name = get_struct_name(struct_ptr, &length);
        if ((name_length == length) && (memcmp(name, name_ptr, length) == 0))
        {
            return struct_ptr;
        }
        struct_ptr = get_next_struct(struct_ptr);
    }
    return NULL;
}

static inline const uint8_t *get_struct(const uint8_t *const ptr,
                                        const char *const name_ptr)
{
    return get_structn(ptr, name_ptr, strlen(name_ptr));
}
//

bool    set_struct_name(const uint8_t *const data)
{
    uint8_t *length_ptr;
    char *name_ptr;

    // increment number of structs
    *structs_array += 1;

    // copy length
    if ((length_ptr = mem_alloc(sizeof(uint8_t))) == NULL)
    {
        return false;
    }
    *length_ptr = data[OFFSET_LC];

    // copy name
    if ((name_ptr = mem_alloc(sizeof(char) * data[OFFSET_LC])) == NULL)
    {
        return false;
    }
    memmove(name_ptr, &data[OFFSET_DATA], data[OFFSET_LC]);

    // initialize number of fields
    if ((current_struct_fields_array = mem_alloc(sizeof(uint8_t))) == NULL)
    {
        return false;
    }
    *current_struct_fields_array = 0;
    return true;
}

bool    set_struct_field(const uint8_t *const data)
{
    uint8_t data_idx = OFFSET_DATA;
    uint8_t *type_desc_ptr;
    uint8_t *type_size_ptr;
    uint8_t *typename_len_ptr;
    char *typename;
    uint8_t *array_levels_count;
    e_array_type *array_level;
    uint8_t *array_level_size;
    uint8_t *fieldname_len_ptr;
    char *fieldname_ptr;

    // increment number of struct fields
    *current_struct_fields_array += 1;

    // copy TypeDesc
    if ((type_desc_ptr = mem_alloc(sizeof(uint8_t))) == NULL)
    {
        return false;
    }
    *type_desc_ptr = data[data_idx++];

    // check TypeSize flag in TypeDesc
    if (*type_desc_ptr & TYPESIZE_MASK)
    {
        // copy TypeSize
        if ((type_size_ptr = mem_alloc(sizeof(uint8_t))) == NULL)
        {
            return false;
        }
        *type_size_ptr = data[data_idx++];
    }
    else if ((*type_desc_ptr & TYPE_MASK) == TYPE_CUSTOM)
    {
        // copy custom struct name length
        if ((typename_len_ptr = mem_alloc(sizeof(uint8_t))) == NULL)
        {
            return false;
        }
        *typename_len_ptr = data[data_idx++];

        // copy name
        if ((typename = mem_alloc(sizeof(char) * *typename_len_ptr)) == NULL)
        {
            return false;
        }
        memmove(typename, &data[data_idx], *typename_len_ptr);
        data_idx += *typename_len_ptr;
    }
    if (*type_desc_ptr & ARRAY_MASK)
    {
        if ((array_levels_count = mem_alloc(sizeof(uint8_t))) == NULL)
        {
            return false;
        }
        *array_levels_count = data[data_idx++];
        for (int idx = 0; idx < *array_levels_count; ++idx)
        {
            if ((array_level = mem_alloc(sizeof(uint8_t))) == NULL)
            {
                return false;
            }
            *array_level = data[data_idx++];
            switch (*array_level)
            {
                case ARRAY_DYNAMIC: // nothing to do
                    break;
                case ARRAY_FIXED_SIZE:
                    if ((array_level_size = mem_alloc(sizeof(uint8_t))) == NULL)
                    {
                        return false;
                    }
                    *array_level_size = data[data_idx++];
                    break;
                default:
                    // should not be in here :^)
                    break;
            }
        }
    }

    // copy length
    if ((fieldname_len_ptr = mem_alloc(sizeof(uint8_t))) == NULL)
    {
        return false;
    }
    *fieldname_len_ptr = data[data_idx++];

    // copy name
    if ((fieldname_ptr = mem_alloc(sizeof(char) * *fieldname_len_ptr)) == NULL)
    {
        return false;
    }
    memmove(fieldname_ptr, &data[data_idx], *fieldname_len_ptr);
    return true;
}

/**
 * Format an unsigned number up to 32-bit into memory into an ASCII string.
 *
 * @param[in] value Value to write in memory
 * @param[in] max_chars Maximum number of characters that could be written
 *
 * @return how many characters have been written in memory, 0 in case of an allocation error
 */
uint8_t format_uint_into_mem(uint32_t value, const uint8_t max_chars)
{
    char        *ptr;
    uint8_t     written_chars;

    if ((ptr = mem_alloc(sizeof(char) * max_chars)) == NULL)
    {
        return 0;
    }
    written_chars = sprintf(ptr, "%u", value);
    mem_dealloc(max_chars - written_chars); // in case it ended up being less
    return written_chars;
}

/**
 *
 *
 * @param[in] struct_ptr pointer to the structure we want the typestring of
 * @param[in] str_length length of the formatted string in memory
 * @return pointer of the string in memory, \ref NULL in case of an error
 */
const char *get_struct_type_string(const uint8_t *const struct_ptr, uint16_t *const str_length)
{
    const char *str_start;
    const char *struct_name;
    uint8_t struct_name_length;
    const uint8_t *field_ptr;
    uint8_t fields_count;
    const char *name;
    uint8_t length;
    uint16_t field_size;
    uint8_t lvls_count;
    const uint8_t *lvl_ptr;
    uint8_t array_size;
    char *char_ptr;
    char *name_ptr;

    // add name
    struct_name = get_struct_name(struct_ptr, &struct_name_length);
    if ((name_ptr = mem_alloc(sizeof(char) * struct_name_length)) == NULL)
    {
        return NULL;
    }
    str_start = memmove(name_ptr, struct_name, struct_name_length);

    if ((char_ptr = mem_alloc(sizeof(char))) == NULL)
    {
        return NULL;
    }
    *char_ptr = '(';

    field_ptr = get_struct_fields_array(struct_ptr, &fields_count);
    for (uint8_t idx = 0; idx < fields_count; ++idx)
    {
        if (idx > 0)
        {
            if ((char_ptr = mem_alloc(sizeof(char))) == NULL)
            {
                return NULL;
            }
            *char_ptr = ',';
        }

        name = get_struct_field_typename(field_ptr, &length);

        if ((name_ptr = mem_alloc(sizeof(char) * length)) == NULL)
        {
            return NULL;
        }
        memmove(name_ptr, name, length);

        if (struct_field_has_typesize(field_ptr))
        {
            field_size = get_struct_field_typesize(field_ptr);
            switch (struct_field_type(field_ptr))
            {
                case TYPE_SOL_INT:
                case TYPE_SOL_UINT:
                    field_size *= 8; // bytes -> bits
                    break;
                case TYPE_SOL_BYTES_FIX:
                    break;
                default:
                    // should not be in here :^)
                    break;
            }
            // max value = 256, 3 characters max
            format_uint_into_mem(field_size, 3);
        }

        if (struct_field_is_array(field_ptr))
        {
            lvl_ptr = get_struct_field_array_lvls_array(field_ptr, &lvls_count);
            while (lvls_count-- > 0)
            {
                if ((char_ptr = mem_alloc(sizeof(char))) == NULL)
                {
                    return NULL;
                }
                *char_ptr = '[';
                switch (struct_field_array_depth(lvl_ptr, &array_size))
                {
                    case ARRAY_DYNAMIC:
                        break;
                    case ARRAY_FIXED_SIZE:
                        // max value = 255, 3 characters max
                        format_uint_into_mem(array_size, 3);
                        break;
                    default:
                        // should not be in here :^)
                        break;
                }
                if ((char_ptr = mem_alloc(sizeof(char))) == NULL)
                {
                    return NULL;
                }
                *char_ptr = ']';
                lvl_ptr = get_next_struct_field_array_lvl(lvl_ptr);
            }
        }
        if ((char_ptr = mem_alloc(sizeof(char))) == NULL)
        {
            return NULL;
        }
        *char_ptr = ' ';
        name = get_struct_field_keyname(field_ptr, &length);

        if ((name_ptr = mem_alloc(sizeof(char) * length)) == NULL)
        {
            return NULL;
        }
        memmove(name_ptr, name, length);

        field_ptr = get_next_struct_field(field_ptr);
    }
    if ((char_ptr = mem_alloc(sizeof(char))) == NULL)
    {
        return NULL;
    }
    *char_ptr = ')';

    *str_length = ((char*)mem_alloc(0) - str_start);
    return str_start;
}

/**
 *
 *
 * @param[in] structs_array pointer to structs array
 * @param[in] deps_count count of how many struct dependencies pointers
 * @param[in,out] dep pointer to the first dependency pointer
 */
void    sort_dependencies(const uint8_t *const deps_count,
                          void **dep)
{
    bool changed = false;
    void *tmp_ptr;
    const char *name1, *name2;
    uint8_t namelen1, namelen2;
    int str_cmp_result;

    for (size_t idx = 0; (idx + 1) < *deps_count; ++idx)
    {
        name1 = get_struct_name(*(dep + idx), &namelen1);
        name2 = get_struct_name(*(dep + idx + 1), &namelen2);

        str_cmp_result = strncmp(name1, name2, MIN(namelen1, namelen2));
        if ((str_cmp_result > 0) || ((str_cmp_result == 0) && (namelen1 > namelen2)))
        {
            tmp_ptr = *(dep + idx);
            *(dep + idx) = *(dep + idx + 1);
            *(dep + idx + 1) = tmp_ptr;

            changed = true;
        }
    }
    // recurse until it is sorted
    if (changed)
    {
        sort_dependencies(deps_count, dep);
    }
}

/**
 *
 *
 * @param[in] structs_array pointer to structs array
 * @param[out] deps_count count of how many struct dependencie pointers
 * @param[in] dep pointer to the first dependency pointer
 * @param[in] struct_ptr pointer to the struct we are getting the dependencies of
 * @return \ref false in case of a memory allocation error, \ref true otherwise
 */
bool    get_struct_dependencies(const void *const structs_array,
                                uint8_t *const deps_count,
                                void **dep,
                                const void *const struct_ptr)
{
    uint8_t fields_count;
    const void *field_ptr;
    const char *arg_structname;
    uint8_t arg_structname_length;
    const void *arg_struct_ptr;
    size_t dep_idx;
    const void **new_dep;

    field_ptr = get_struct_fields_array(struct_ptr, &fields_count);
    for (uint8_t idx = 0; idx < fields_count; ++idx)
    {
        if (struct_field_type(field_ptr) == TYPE_CUSTOM)
        {
            // get struct name
            arg_structname = get_struct_field_typename(field_ptr, &arg_structname_length);
            // from its name, get the pointer to its definition
            arg_struct_ptr = get_structn(structs_array, arg_structname, arg_structname_length);

            // check if it is not already present in the dependencies array
            for (dep_idx = 0; dep_idx < *deps_count; ++dep_idx)
            {
                // it's a match!
                if (*(dep + dep_idx) == arg_struct_ptr)
                {
                    break;
                }
            }
            // if it's not present in the array, add it and recurse into it
            if (dep_idx == *deps_count)
            {
                if ((new_dep = mem_alloc(sizeof(void*))) == NULL)
                {
                    return false;
                }
                *new_dep = arg_struct_ptr;
                *deps_count += 1;
                get_struct_dependencies(structs_array, deps_count, dep, arg_struct_ptr);
            }
        }
        field_ptr = get_next_struct_field(field_ptr);
    }
    return true;
}

/**
 *
 *
 * @param[in] structs_array pointer to structs array
 * @param[in] struct_name name of the given struct
 * @param[in] struct_name_length length of the name of the given struct
 * @return \ref false in case of a memory allocation error, \ref true otherwise
 */
bool    get_type_hash(const void *const structs_array,
                      const char *const struct_name,
                      const uint8_t struct_name_length)
{
    const void *const struct_ptr = get_structn(structs_array,
                                               struct_name,
                                               struct_name_length);
    const void *const mem_loc_bak = mem_alloc(0); // backup the memory location
    uint8_t *deps_count;
    void **dep;
    uint16_t total_length = 0;
    uint16_t length;
    const char *typestr;

    if ((deps_count = mem_alloc(sizeof(uint8_t))) == NULL)
    {
        return false;
    }
    *deps_count = 0;
    // get list of structs (own + dependencies), properly ordered
    dep = (void**)(deps_count + 1); // get first elem
    if (get_struct_dependencies(structs_array, deps_count, dep, struct_ptr) == false)
    {
        return false;
    }
    sort_dependencies(deps_count, dep);
    typestr = get_struct_type_string(struct_ptr, &length);
    total_length += length;
    // loop over each struct and generate string
    for (int idx = 0; idx < *deps_count; ++idx)
    {
        get_struct_type_string(*dep, &length);
        total_length += length;
        dep += 1;
    }

    fwrite(typestr, sizeof(char), total_length, stdout);
    printf("\n");

    // restore the memory location
    mem_dealloc(mem_alloc(0) - mem_loc_bak);
    return true;
}

bool    handle_apdu(const uint8_t *const data)
{
    switch (data[OFFSET_INS])
    {
        case INS_STRUCT_DEF:
            switch (data[OFFSET_P2])
            {
                case P2_NAME:
                    set_struct_name(data);
                    break;
                case P2_FIELD:
                    set_struct_field(data);
                    break;
                default:
                    printf("Unknown P2 0x%x for APDU 0x%x\n", data[OFFSET_P2], data[OFFSET_INS]);
                    return false;
            }
            break;
        case INS_STRUCT_IMPL:
            switch (data[OFFSET_P2])
            {
                case P2_NAME:
                    get_type_hash(structs_array, (char*)&data[OFFSET_DATA], data[OFFSET_LC]);
                    break;
                case P2_FIELD:
                    break;
                case P2_ARRAY:
                    break;
                default:
                    printf("Unknown P2 0x%x for APDU 0x%x\n", data[OFFSET_P2], data[OFFSET_INS]);
                    return false;
            }
            break;
        default:
            printf("Unrecognized APDU (0x%.02x)\n", data[OFFSET_INS]);
            return false;
    }
    return true;
}

bool    init_typenames(void)
{
    const char *const typenames_str[] = {
        "int",
        "uint",
        "address",
        "bool",
        "string",
        "byte",
        "bytes"
    };
    const int enum_to_idx[][IDX_COUNT] = {
        { TYPE_SOL_INT, 0 },
        { TYPE_SOL_UINT, 1},
        { TYPE_SOL_ADDRESS, 2 },
        { TYPE_SOL_BOOL, 3 },
        { TYPE_SOL_STRING, 4 },
        { TYPE_SOL_BYTE, 5 },
        { TYPE_SOL_BYTES_FIX, 6 },
        { TYPE_SOL_BYTES_DYN, 6 }
    };
    uint8_t *previous_match;
    uint8_t *typename_len_ptr;
    char *typename_ptr;

    if ((typenames_array = mem_alloc(sizeof(uint8_t))) == NULL)
    {
        return false;
    }
    *typenames_array = 0;
    // loop over typenames
    for (size_t s_idx = 0;
         s_idx < (sizeof(typenames_str) / sizeof(typenames_str[IDX_ENUM]));
         ++s_idx)
    {
        previous_match = NULL;
        // loop over enum/typename pairs
        for (size_t e_idx = 0;
             e_idx < (sizeof(enum_to_idx) / sizeof(enum_to_idx[IDX_ENUM]));
             ++e_idx)
        {
            if (s_idx == (size_t)enum_to_idx[e_idx][IDX_STR_IDX]) // match
            {
                if (previous_match) // in case of a previous match, mark it
                {
                    *previous_match |= TYPENAME_MORE_TYPE;
                }
                if ((previous_match = mem_alloc(sizeof(uint8_t))) == NULL)
                {
                    return false;
                }
                *previous_match = enum_to_idx[e_idx][IDX_ENUM];
            }
        }

        if (previous_match) // if at least one match was found
        {
            if ((typename_len_ptr = mem_alloc(sizeof(uint8_t))) == NULL)
            {
                return false;
            }
            // get pointer to the allocated space just above
            *typename_len_ptr = strlen(typenames_str[s_idx]);


            if ((typename_ptr = mem_alloc(sizeof(char) * *typename_len_ptr)) == NULL)
            {
                return false;
            }
            // copy typename
            memcpy(typename_ptr, typenames_str[s_idx], *typename_len_ptr);
        }
        // increment array size
        *typenames_array += 1;
    }
    return true;
}

bool    init_eip712_context(void)
{
    // init global variables
    init_mem();

    if (init_typenames() == false)
        return false;

    // set types pointer
    if ((structs_array = mem_alloc(sizeof(uint8_t))) == NULL)
        return false;

    // create len(types)
    *structs_array = 0;
    return true;
}

int     main(void)
{
    uint8_t         buf[260]; // 4 bytes APDU header + 256 bytes payload
    uint16_t        idx;
    int             state;
    uint8_t         payload_size = 0;

    init_eip712_context();

    state = OFFSET_CLA;
    idx = 0;
    while (fread(&buf[idx], sizeof(buf[idx]), 1, stdin) > 0)
    {
        switch (state)
        {
            case OFFSET_CLA:
            case OFFSET_INS:
            case OFFSET_P1:
            case OFFSET_P2:
                state += 1;
                idx += 1;
                break;
            case OFFSET_LC:
                payload_size = buf[idx];
                state = OFFSET_DATA;
                idx += 1;
                break;
            case OFFSET_DATA:
                if (--payload_size == 0)
                {
                    if (!handle_apdu(buf)) return false;
                    state = OFFSET_CLA;
                    idx = 0;
                }
                else idx += 1;
                break;
            default:
                printf("Unexpected APDU state!\n");
                return EXIT_FAILURE;
        }
    }
#ifdef DEBUG
    printf("\n%lu bytes used in RAM\n", (mem_max + 1));
#endif
    return EXIT_SUCCESS;
}