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

#include "util.h"
#include "spec.h"

#define ARRAY_COUNT(arr) (sizeof(arr) / sizeof(arr[0]))

static struct Segment *add_segment(struct Segment **segments, int *segments_count)
{
    struct Segment *seg;

    (*segments_count)++;
    *segments = realloc(*segments, *segments_count * sizeof(**segments));

    seg = &(*segments)[*segments_count - 1];
    memset(seg, 0, sizeof(*seg));

    seg->align = 16;

    return seg;
}

static char *skip_whitespace(char *str)
{
    while (isspace(*str))
        str++;
    return str;
}

// null terminates the current token and returns a pointer to the next token
static char *token_split(char *str)
{
    while (!isspace(*str))
    {
        if (*str == 0)
            return str;  // end of string
        str++;
    }
    *str = 0;  // terminate token
    str++;

    return skip_whitespace(str);
}

// null terminates the current line and returns a pointer to the next line
static char *line_split(char *str)
{
    while (*str != '\n')
    {
        if (*str == 0)
            return str;  // end of string
        str++;
    }
    *str = 0;  // terminate line
    return str + 1;
}

static bool parse_number(const char *str, unsigned int *num)
{
    char *endptr;
    long int n = strtol(str, &endptr, 0);
    *num = n;
    return endptr > str;
}

static bool parse_flags(char *str, unsigned int *flags)
{
    unsigned int f = 0;

    while (str[0] != 0)
    {
        char *next = token_split(str);

        if (strcmp(str, "BOOT") == 0)
            f |= FLAG_BOOT;
        else if (strcmp(str, "OBJECT") == 0)
            f |= FLAG_OBJECT;
        else if (strcmp(str, "RAW") == 0)
            f |= FLAG_RAW;
        else if (strcmp(str, "NOLOAD") == 0)
            f |= FLAG_NOLOAD;
        else if (strcmp(str, "SYMS") == 0)
            f |= FLAG_SYMS;
        else
            return false;

        str = next;
    }
    *flags = f;
    return true;
}

static bool parse_quoted_string(char *str, char **out)
{
    if (*str != '"')
        return false;

    str++;
    *out = str;

    while (*str != '"')
    {
        if (*str == 0)
            return false;  // unterminated quote
        str++;
    }
    *str = 0;
    str++;

    str = skip_whitespace(str);
    if (*str != 0)
        return false;  // garbage after filename

    return true;
}

static bool is_pow_of_2(unsigned int n)
{
    return (n & (n - 1)) == 0;
}

static const char *const stmtNames[] =
{
    [STMT_address]   = "address",
    [STMT_after]     = "after",
    [STMT_align]     = "align",
    [STMT_beginseg]  = "beginseg",
    [STMT_compress]  = "compress",
    [STMT_endseg]    = "endseg",
    [STMT_entry]     = "entry",
    [STMT_flags]     = "flags",
    [STMT_include]   = "include",
    [STMT_name]      = "name",
    [STMT_number]    = "number",
    [STMT_romalign]  = "romalign",
    [STMT_stack]     = "stack",
    [STMT_increment] = "increment",
    [STMT_pad_text]  = "pad_text",
};

STMTId get_stmt_id_by_stmt_name(const char *stmtName, int lineNum) {
    STMTId stmt;

    for (stmt = 0; stmt < ARRAY_COUNT(stmtNames); stmt++) {
        if (strcmp(stmtName, stmtNames[stmt]) == 0)
        return stmt;
    }
    util_fatal_error("line %i: unknown statement '%s'", lineNum, stmtName);
    return -1;
}

bool parse_segment_statement(struct Segment *currSeg, STMTId stmt, char* args, int lineNum) {
    // ensure no duplicates (except for 'include' or 'pad_text')
    if (stmt != STMT_include && stmt != STMT_pad_text &&
        (currSeg->fields & (1 << stmt)))
        util_fatal_error("line %i: duplicate '%s' statement", lineNum, stmtNames[stmt]);

    currSeg->fields |= 1 << stmt;

    // statements valid within a segment definition
    switch (stmt)
    {
    case STMT_beginseg:
        util_fatal_error("line %i: '%s' inside of a segment definition", lineNum, stmtNames[stmt]);
        break;
    case STMT_endseg:
        // verify segment data
        if (currSeg->name == NULL)
            util_fatal_error("line %i: no name specified for segment", lineNum);
        if (currSeg->includesCount == 0)
            util_fatal_error("line %i: no includes specified for segment", lineNum);
        return true;
        break;
    case STMT_name:
        if (!parse_quoted_string(args, &currSeg->name))
            util_fatal_error("line %i: invalid name", lineNum);
        break;
    case STMT_after:
        if (!parse_quoted_string(args, &currSeg->after))
            util_fatal_error("line %i: invalid name for 'after'", lineNum);
        break;
    case STMT_address:
        if (!parse_number(args, &currSeg->address))
            util_fatal_error("line %i: expected number after 'address'", lineNum);
        break;
    case STMT_number:
        if (!parse_number(args, &currSeg->number))
            util_fatal_error("line %i: expected number after 'number'", lineNum);
        break;
    case STMT_flags:
        if (!parse_flags(args, &currSeg->flags))
            util_fatal_error("line %i: invalid flags", lineNum);
        break;
    case STMT_align:
        if (!parse_number(args, &currSeg->align))
            util_fatal_error("line %i: expected number after 'align'", lineNum);
        if (!is_pow_of_2(currSeg->align))
            util_fatal_error("line %i: alignment is not a power of two", lineNum);
        break;
    case STMT_romalign:
        if (!parse_number(args, &currSeg->romalign))
            util_fatal_error("line %i: expected number after 'romalign'", lineNum);
        if (!is_pow_of_2(currSeg->romalign))
            util_fatal_error("line %i: alignment is not a power of two", lineNum);
        break;
    case STMT_include:
        currSeg->includesCount++;
        currSeg->includes = realloc(currSeg->includes, currSeg->includesCount * sizeof(*currSeg->includes));

        if (!parse_quoted_string(args, &currSeg->includes[currSeg->includesCount - 1].fpath))
            util_fatal_error("line %i: invalid filename", lineNum);

        currSeg->includes[currSeg->includesCount - 1].linkerPadding = 0;
        break;
    case STMT_increment:
        if (!parse_number(args, &currSeg->increment))
            util_fatal_error("line %i: expected number after 'increment'", lineNum);
        break;
    case STMT_compress:
        currSeg->compress = true;
        break;
    case STMT_pad_text:
        currSeg->includes[currSeg->includesCount - 1].linkerPadding += 0x10;
        break;
    default:
        fprintf(stderr, "warning: '%s' is not implemented\n", stmtNames[stmt]);
        break;
    }
    return false;
}

/**
 * `segments` should be freed with `free_rom_spec` after use.
 * Will write to the contents of `spec` to introduce string terminating '\0's.
 * `segments` also contains pointers to inside `spec`, so `spec` should not be freed before `segments`
 */
void parse_rom_spec(char *spec, struct Segment **segments, int *segment_count)
{
    int lineNum = 1;
    char *line = spec;

    struct Segment *currSeg = NULL;

    // iterate over lines
    while (line[0] != 0)
    {
        char *nextLine = line_split(line);
        char* stmtName;

        if (line[0] != 0)
        {
            stmtName = skip_whitespace(line);
        }

        if (line[0] != 0 && stmtName[0] != 0)
        {
            char *args = token_split(stmtName);
            STMTId stmt = get_stmt_id_by_stmt_name(stmtName, lineNum);

            if (currSeg != NULL)
            {
                bool segmentEnded = parse_segment_statement(currSeg, stmt, args, lineNum);
                if (segmentEnded) {
                    currSeg = NULL;
                }
            }
            else
            {
                // commands valid outside a segment definition
                switch (stmt)
                {
                case STMT_beginseg:
                    currSeg = add_segment(segments, segment_count);
                    currSeg->includes = NULL;
                    break;
                case STMT_endseg:
                    util_fatal_error("line %i: '%s' outside of a segment definition", lineNum, stmtName);
                    break;
                default:
                    fprintf(stderr, "warning: '%s' is not implemented\n", stmtName);
                    break;
                }
            }
        }

        line = nextLine;
        lineNum++;
    }
}

/**
 * @brief Parses the spec, looking only for the segment with the name `segmentName`.
 * Returns true if the segment was found, false otherwise
 *
 * @param[out] dstSegment The Segment to be filled. Will only contain the data of the searched segment, or garbage if the segment was not found. dstSegment must be previously allocated, a stack variable is recommended
 * @param[in,out] spec A null-terminated string containing the whole spec file. This string will be modified by this function
 * @param[in] segmentName The name of the segment being searched
 */
bool get_single_segment_by_name(struct Segment* dstSegment, char *spec, const char *segmentName) {
    bool insideSegment = false;
    int lineNum = 1;
    char *line = spec;

    memset(dstSegment, 0, sizeof(struct Segment));

    // iterate over lines
    while (line[0] != '\0') {
        char *nextLine = line_split(line);
        char* stmtName = skip_whitespace(line);

        if (stmtName[0] != '\0') {
            char *args = token_split(stmtName);
            STMTId stmt = get_stmt_id_by_stmt_name(stmtName, lineNum);

            if (insideSegment) {
                bool segmentEnded = parse_segment_statement(dstSegment, stmt, args, lineNum);

                if (stmt == STMT_name) {
                    if (strcmp(segmentName, dstSegment->name) != 0) {
                        // Not the segment we are looking for
                        insideSegment = false;
                    }
                } else if (segmentEnded) {
                    return true;
                }
            } else {
                if (stmt == STMT_beginseg) {
                    insideSegment = true;
                    if (dstSegment->includes != NULL) {
                        free(dstSegment->includes);
                    }
                    memset(dstSegment, 0, sizeof(struct Segment));
                }
            }
        }

        line = nextLine;
        lineNum++;
    }

    return false;
}

/**
 * @brief Frees the elements of the passed Segment. Will not free the pointer itself
 *
 * @param segment
 */
void free_single_segment_elements(struct Segment *segment) {
    if (segment->includes != NULL) {
        free(segment->includes);
    }
}

void free_rom_spec(struct Segment *segments, int segment_count)
{
    int i;

    for (i = 0; i < segment_count; i++)
    {
        if (segments[i].includes != NULL)
            free(segments[i].includes);
    }
    free(segments);
}