#include <getopt.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#define BOOKI_FILE_REL ".local/share/booki/books.toml"

#define MAX_SEARCH_OPTS 5

// STRUCTS
struct es {
    int len;
    char* ptr;
};

struct es default_es = { 0, NULL };

struct Book {
    struct es id;
    struct es title;
    struct es author;
    int pages;
    struct es isbn;
    struct es language;
    struct es translator;
    int published;

    // maybe?
    //struct es authors[MAX_AUTHORS];
    //struct es translators[MAX_TRANSLATORS];
};

struct Book new_book() {
    struct Book book;
    book.id = default_es;
    book.title = default_es;
    book.author = default_es;
    book.pages = 0;
    book.isbn = default_es;
    struct es language = { 7, "English" };  // default language
    book.language = language;
    book.translator = default_es;
    book.published = 0;
    return book;
}

char* BOOKI_FILE;

int PARSE_LINE = 1;

const char* get_last_word(const char* str) {
    const char* last_space = strrchr(str, ' ');
    if ((last_space - str) > 0)
        return last_space + 1;
    else
        return 0;
}

struct Book parse_book(char* current_pos) {
    struct Book book = new_book();
    char* attr;
    char* value;
    char c = *current_pos;
    // loop until we hit the extra newline
    while (c != '\n') {
        // we start at the beginning of a line
        attr = current_pos;
        while ((c = *current_pos) != '=') {
            current_pos++;
        }

        // attr should be the name of the attribute, with (possibly) trailing spaces
        if (strncmp(attr, "title", 5) == 0) {
            // leading spaces
            while ((c = *current_pos) != '"') {
                current_pos++;
            }

            // go past the quote and set the position of the start of value
            current_pos++;
            value = current_pos;

            // until the next quote
            while ((c = *current_pos) != '"') {
                current_pos++;
            }

            // set the attribute
            struct es title;
            title.len = current_pos - value;
            title.ptr = value;
            book.title = title;
        } else if (strncmp(attr, "author", 6) == 0) {
            // leading spaces
            while ((c = *current_pos) != '"') {
                current_pos++;
            }

            // go past the quote and set the position of the start of value
            current_pos++;
            value = current_pos;

            // until the next quote
            while ((c = *current_pos) != '"') {
                current_pos++;
            }

            // set the attribute
            struct es author;
            author.len = current_pos - value;
            author.ptr = value;
            book.author = author;
        }

        // go to (and then past) the newline
        while ((c = *current_pos) != '\n') {
            current_pos++;
        }
        PARSE_LINE += 1;
        c = *(++current_pos);
    }
    return book;
}

char* next_book(char* current_pos) {
    char c;
    while(*current_pos) {
        // first opening bracket
        c = *current_pos++;
        if (c != '[') {
            continue;
        }
        
        // second opening bracket
        c = *current_pos++;
        if (c != '[') {
            continue;
        }

        if (strncmp(current_pos, "books", 5) != 0) {
            printf("thought i had it, but it's not a book\n");
            continue;
        }
        current_pos += 5;

        // seek past the closing brackets and the next newline
        current_pos += 2;
        if (*current_pos != '\n') {
            printf("expecting a newline...\n");
            continue;
        }

        PARSE_LINE += 1;
        current_pos++;
        return current_pos;
    }
    return NULL;
}

bool regex_match(const char* pattern, const struct es text) {

    // empty pattern matches everything
    if (!*pattern) return true;

    // get lengths
    int pattern_length = strlen(pattern);

    if (pattern_length > text.len) return false;

    // we only need to compare while remaining text is
    // as long or longer than pattern (without special)
    for (int i = 0; i <= (text.len - pattern_length); i++) {
        if (strncasecmp(pattern, text.ptr + i, pattern_length) == 0) return true;
    }

    return false;
}

char* load_file(char* filename) {
    // open the file
    FILE* fp = fopen(filename, "r");
    if (!fp) {
        printf("bad file\n");
        return NULL;
    }

    // seek to the end
    fseek(fp, 0, SEEK_END);
    int size = ftell(fp);
    rewind(fp);

    char* data = malloc(size);
    if (!data) {
        printf("couldn't malloc\n");
        return NULL;
    }

    int read_size = fread(data, 1, size, fp);
    if (read_size != size) {
        printf("didn't read everything -- %d read of %d\n", read_size, size);
        return NULL;
    }

    fclose(fp);

    return data;
}

static struct option search_options[] = {
    {"show", no_argument, 0, 's'},
    {0, 0, 0, 0}  // marks the end of the array
};

struct search_opt {
    int show;
    int count;
    char* opts[MAX_SEARCH_OPTS];
    char* args[MAX_SEARCH_OPTS];
};

struct search_opt parse_search_options(int argc, char* argv[]) {

    // return struct
    struct search_opt opt_out;
    int count = 0;
    int show = false;

    // opt options
    int opt;
    int opt_idx = 0;
    opterr = 0;  // turn off getopt error messages

    // look at each option
    while ((opt = getopt_long_only(argc, argv, "", search_options, &opt_idx)) != -1) {
        switch(opt) {
            case 's':
                show = true;
                break;
            case '?':
                // optind points at the argument (one past the option)
                opt_out.opts[count] = argv[optind-1] + 2;  // '--example' -> 'example'
                opt_out.args[count] = argv[optind];
                count++;
                break;
            default:
                printf("something went wrong with parsing!\n");
                break;
        }
    }

    // set the count/show values
    opt_out.count = count;
    opt_out.show = show;

    return opt_out;
}

void print_book(struct Book book, bool all_fields) {
    printf("%.*s by %.*s\n", book.title.len, book.title.ptr, book.author.len, book.author.ptr);
    if (all_fields) {
        char* esfmt = " - %s: %.*s\n";
        char* intfmt = " - %s: %d\n";
        if (book.isbn.ptr)
            printf(esfmt, "isbn", book.isbn.len, book.isbn.ptr);
        if (book.pages != 0)
            printf(intfmt, "pages", book.pages);
        if (book.published)
            printf(esfmt, "published", book.published);
        if (book.language.ptr)
            printf(esfmt, "language", book.language.len, book.language.ptr);
        if (book.translator.ptr)
            printf(esfmt, "translator", book.translator.len, book.translator.ptr);

    }
}

char** search(int argc, char* argv[]) {
    struct search_opt search_opts = parse_search_options(argc, argv);
    bool print = false;

    // get the books array
    char* data = load_file(BOOKI_FILE);
    if (!data) {
        printf("no such array: 'books'");
        return NULL;
    }

    // book loop
    struct Book book;
    char* cur_data = data;
    while ((cur_data = next_book(cur_data)) != NULL) {
        book = parse_book(cur_data);

        char* field;
        int i;
        bool print = true;
        for (i = 0; i < search_opts.count; i++) {
            field = search_opts.opts[i];

            // compare fields
            if (strcmp(field, "title") == 0) {
                if (!regex_match(search_opts.args[i], book.title))
                    break;
            } else if (strcmp(field, "author") == 0) {
                if (!regex_match(search_opts.args[i], book.author))
                    break;
            } else {
                printf("unsupported field: %s\n", field);
                break;
            }
        }
        print = i == search_opts.count;

        if (print) {
            print_book(book, search_opts.show);
        }
    }

    free(data);

    return argv + optind;
}


void open() {

    char* home = getenv("HOME");
    if (!home) {
        printf("no home?\n");
        home = "/";  // no way
    }
    char* editor = getenv("EDITOR");
    if (!editor)
        editor = "nano";

    pid_t pid;
    int status;
    switch ((pid = fork())) {
        case -1:
            printf("fork has failed!\n");
            break;
        case 0:
            execlp(editor, editor, BOOKI_FILE, NULL);
            printf("child failed :(\n");
            break;
        default:
            // wait for the child to finish
            pid = wait(&status);
            break;
    }
}

void help(bool err) {
    printf("booki! it's a thing\n");
    if (err) {
        printf("you did something wrong\n");
    }
}

int main(int argc, char* argv[]) {

    char* home = getenv("HOME");
    char booki_file[strlen(home) + strlen(BOOKI_FILE_REL) + 1];
    sprintf(booki_file, "%s/%s", home, BOOKI_FILE_REL);
    BOOKI_FILE = booki_file;
    char** remaining = NULL;

    if (argc == 1) {
        help(false);
        return 0;
    } else if (strcmp(argv[1], "open") == 0) {
        open();
    } else if (strcmp(argv[1], "search") == 0) {
        remaining = search(argc - 1, argv + 1);
    }

    return 0;
}