#include <errno.h>
#include <stdio.h>
#include <string.h>

#include "file.h"


const char* basename(const char* filename) {
    const char* slash = filename + strlen(filename) - 1;
    for ( ; slash >= filename &&
            *slash != '\\' &&
            *slash != '/';
            --slash );
    return &slash[1];
}

int make_filename(char* filename, int max_len,
                  const char* orig_name,
                  const char* subdir, const char* ext) {
    int status = 0;
    int remain = max_len;

    const char* orig_base = basename(orig_name);
    const char* orig_dot = strrchr(orig_base, '.');

    int orig_path_len = orig_base - orig_name;

    int orig_base_len = (NULL == orig_dot) ?
                        strlen(orig_base) :
                        (orig_dot - orig_base);

    // Part 1/4: Leading path
    if (0 == status && orig_path_len <= remain) {
        memcpy(filename, orig_name, orig_path_len);
        remain -= orig_path_len;
        filename += orig_path_len;
    } else {
        status = -1;
    }

    // Part 2/4: Subdirectory
    if (0 == status && NULL != subdir) {
        int subdir_len = strlen(subdir);
        if ((subdir_len + 1) <= remain) {
            memcpy(filename, subdir, subdir_len);
            filename += subdir_len;
            *filename++ = '/';
            remain -= (subdir_len + 1);
        } else {
            status = -1;
        }
    }

    // Part 3/4: Basename
    if (0 == status && orig_base_len <= remain) {
        memcpy(filename, orig_name, orig_base_len);
        remain -= orig_base_len;
        filename += orig_base_len;
    } else {
        status = -1;
    }

    // Part 4/4: Extension
    if (0 == status && NULL != ext) {
        int ext_len = strlen(ext);
        if ((ext_len + 1) <= remain) {
            *filename++ = '.';
            memcpy(filename, ext, ext_len);
            remain -= (ext_len + 1);
            filename += ext_len;
        } else {
            status = -1;
        }
    }

    return (status < 0 ? status : (max_len - remain));
}


int write_file(const char* filename, const void* data, int len) {
    int status = -1;

    FILE* file = fopen(filename, "wb");
    if (NULL != file) {
        if (1 == fwrite(data, len, 1, file)) {
            status = 0;
        } else {
            fprintf(stderr, "Failed to write %d bytes from %s: %d\n", len, filename, errno);
        }
        fclose(file);
    } else {
        fprintf(stderr, "Failed to open %s: %d\n", filename, errno);
    }

    return status;
}


int read_file(const char* filename, void* data, int len) {
    int status = -1;

    FILE* file = fopen(filename, "rb");
    if (NULL != file) {
        if (1 == fread(data, len, 1, file)) {
            status = 0;
        } else {
            fprintf(stderr, "Failed to read %d bytes from %s: %d\n", len, filename, errno);
        }
        fclose(file);
    } else {
        fprintf(stderr, "Failed to open %s: %d\n", filename, errno);
    }

    return status;
}