#include "../command.h"
#include <stdio.h>

static struct {
    bool filename_prefix;
    bool never_file_prefix;
    bool line_number;
    bool only_matching_names;
    bool only_non_matching_names;
    bool only_line_count;
    bool only_matching_part;
    bool quiet;
    bool inverse;
    bool ignore_case;
    bool is_regex;
} flags;

static int short_arg(char c, char* next) {
    UNUSED(next);
    switch (c) {
        case 'H':
            flags.filename_prefix = true;
            break;
        case 'h':
            flags.never_file_prefix = true;
            break;
        case 'n':
            flags.line_number = true;
            break;
        case 'l':
            flags.only_matching_names = true;
            break;
        case 'L':
            flags.only_non_matching_names = true;
            break;
        case 'c':
            flags.only_line_count = true;
            break;
        case 'o':
            flags.only_matching_part = true;
            break;
        case 'q':
            flags.quiet = true;
            break;
        case 'v':
            flags.inverse = true;
            break;
        case 'i':
            flags.ignore_case = true;
            break;
        case 'F':
            flags.is_regex = false;
            break;
        case 'E':
            flags.is_regex = true;
            break;
        default:
            return ARG_INVALID;
    }
    return ARG_UNUSED;
}

static void help(void) {
    printf("Usage: grep [-HhlLoqviFE] [-m N] PATTERN [FILE]...\n");
    printf("Search for PATTERN in FILEs (or stdin)\n");
    printf("\t-H\tAdd 'filename:' prefix\n");
    printf("\t-h\tDo not add 'filename:' prefix\n");
    printf("\t-n\tAdd 'line_no:' prefix\n");
    printf("\t-l\tShow only names of files that match\n");
    printf("\t-L\tShow only names of files that don't match\n");
    printf("\t-c\tShow only count of matching lines\n");
    printf("\t-o\tShow only the matching part of line\n");
    printf("\t-q\tQuiet. Return 0 if PATTERN is found, 1 otherwise\n");
    printf("\t-v\tSelect non-matching lines\n");
    printf("\t-i\tIgnore case\n");
    printf("\t-F\tPATTERN is a literal (not regexp)\n");
    printf("\t-E\tPATTERN is an extended regexp\n");
}

static bool match_regex(char** string, re_t pattern) {
    int len;
    int index;
    if ((index = re_matchp(pattern, *string, &len)) < 0) return false;
    if (flags.only_matching_part) {
        (*string) += index;
        (*string)[len] = '\0';
    }
    return true;
}

static bool match_literal(char** string, char* pattern) {
    char* match = *string;
    size_t match_len = strlen(match);
    size_t pattern_len = strlen(pattern);
    size_t i;

    if (match_len < pattern_len) return false;

    for (i = 0; i < match_len - pattern_len + 1; i++) {
        if (
            (!flags.ignore_case && strncmp(match + i, pattern, pattern_len) == 0) ||
            (flags.ignore_case && strncasecmp(match + i, pattern, pattern_len) == 0)
        ) {
            if (flags.only_matching_part) {
                *string = (*string) + i;
                (*string)[pattern_len] = '\0';
            }
            return true;
        }
    }   

    return false;
}

static bool match(char** string, void* pattern) {
    bool result;
    if (flags.is_regex) {
        result =  match_regex(string, (re_t) pattern);
    } else {
        result = match_literal(string, (char*) pattern);
    }
    return (flags.inverse ? !result : result);
}

static bool match_any(char* path, void* pattern) {
    FILE* file;
    char* buf = NULL;
    size_t offset;
    bool matched = false;
    int read;
    
    file = get_file_s(path, "r");
    if (file == NULL) return false;

    while ((read = getline(&buf, &offset, file)) > 0) {
        char* save = buf;
        if (buf[read-1] == '\n') buf[read-1] = '\0';
        if (match(&save, pattern)) {
            matched = true;
            break;
        }
    }

    if (buf != NULL) free(buf);

    return matched;
}

static bool match_file(char* path, void* pattern, bool many) {
    FILE* file;
    char* buf = NULL;
    size_t offset;
    int num_matched = 0;
    int line_num = 0;
    int read;

    file = get_file_s(path, "r");
    if (file == NULL) return false;

    while((read = getline(&buf, &offset, file)) > 0) {
        char* matched = buf;
        
        if (buf[read-1] == '\n') buf[read-1] = '\0';
        line_num++;
        
        if (!match(&matched, pattern)) {
            continue;
        }
        
        num_matched++;
        
        if (flags.only_line_count || flags.quiet) continue;
        
        if ((many || flags.filename_prefix) && !flags.never_file_prefix) {
            print_file_path(path);
            putchar(':');
        }
        
        if (flags.line_number) {
            printf("%d:", line_num);
        }
        
        if (flags.only_matching_part) {
            printf("%s\n", matched);
        } else {
            printf("%s\n", buf);
        }
    }

    if (!flags.quiet && flags.only_line_count) {
        if ((many || flags.filename_prefix) && !flags.never_file_prefix) {
            print_file_path(path);
            putchar(':');
        }
        printf("%d\n", num_matched);
    }

    if (buf != NULL) free(buf);

    return num_matched != 0;
}

static void* compile(char* pattern) {
    if (flags.is_regex) {
        return re_compile(pattern);
    } else {
        return pattern;
    }
}

static bool run_match(char* path, void* pattern, bool many) {
    bool result;
    if (flags.only_matching_names || flags.only_non_matching_names) {
        result = match_any(path, pattern);
        if (flags.only_non_matching_names) result = !result;
        if (result && !flags.quiet) {
            print_file_path(path);
            putchar('\n');
        }
        return result;
    } else {
        return match_file(path, pattern, many);
    }
}

COMMAND(grep) {

    int start, i;
    char* pattern;
    bool many, ok;
    void* compiled;

    flags.only_matching_part = false;
    flags.only_non_matching_names = false;
    flags.only_matching_names = false;
    flags.only_line_count = false;
    flags.quiet = false;
    flags.is_regex = true;
    flags.line_number = false;
    flags.never_file_prefix = false;
    flags.filename_prefix = false;
    flags.inverse = false;

    start = parse_args(argc, argv, help, short_arg, NULL);

    if (argc - start < 1) global_help(help);

    pattern = argv[start++];
        
    many = argc - start > 0;
    ok = false;

    compiled = compile(pattern);
    if (run_match("-", compiled, many)) ok = true;

    for (i = start; i < argc; i++) {
        if (run_match(argv[i], compiled, many)) ok = true;
    }

    if (flags.quiet) {
        return ok ? EXIT_SUCCESS : EXIT_FAILURE;
    } else {
        return EXIT_SUCCESS;
    }
}