#ifndef STR_H
#define STR_H

#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>

typedef struct {
    uint8_t *data;
    size_t len;
} str;

typedef struct {
    bool found;
    size_t offset;
} str_find_result;

#define STR(s) (str) { .data = (uint8_t *) s, .len = sizeof(s) - 1 }

str make_str(uint8_t *data, size_t len);
str cstr(const char *cstr);
str str_next_token(str *source, str delim);
str str_sub(str s, size_t start, size_t end);
str str_trim_left(str s);
str str_trim_right(str s);
str str_trim(str s);
bool str_eq(str a, str b);
bool str_starts_with(str s, str prefix);
bool str_ends_with(str s, str suffix);
bool str_empty(str s);
void str_split(str s, str delim, str *first, str *second);

str_find_result str_find_left(str haystack, str needle);
str_find_result str_find_right(str haystack, str needle);

void str_print(str s);

#define STR_FMT "%.*s"
#define STR_ARG(s) (int) (s).len, (const char *) (s).data

#ifdef STR_IMPLEMENTATION

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

str make_str(uint8_t *data, size_t len) {
    return (str) { .data = data, .len = len };
}

str cstr(const char *cstr) {
    size_t len = 0;
    for (const char *it = cstr; *it; ++it) {
        len++;
    }
    return (str) {
        .data = (uint8_t *) cstr,
        .len = len
    };
}

str str_sub(str s, size_t start, size_t end) {
    return (str) {
        .data = s.data + start,
        .len = end - start
    };
}

static inline bool is_whitespace(int ch) {
    return ch == ' ' || ch == '\r' || ch == '\n'
        || ch == '\t' || ch == '\v' || ch == '\f';
}

str str_trim_left(str s) {
    // TODO make more efficient!
    while (s.len > 0 && is_whitespace(s.data[0])) {
        s.data++;
        s.len--;
    }
    return s;
}

str str_trim_right(str s) {
    // TODO make more efficient!
    while (s.len > 0 && is_whitespace(s.data[s.len - 1])) {
        s.len--;
    }
    return s;
}

str str_trim(str s) {
    return str_trim_right(str_trim_left(s));
}

bool str_eq(str a, str b) {
    if (a.len != b.len) {
        return false;
    }
    else {
        for (size_t i = 0; i < a.len; ++i) {
            if (a.data[i] != b.data[i]) {
                return false;
            }
        }
        return true;
    }
}

bool str_starts_with(str s, str prefix) {
    if (prefix.len > s.len) {
        return false;
    }
    return memcmp(s.data, prefix.data, prefix.len) == 0;
}

bool str_ends_with(str s, str suffix) {
    if (suffix.len > s.len) {
        return false;
    }
    return memcmp(s.data + s.len - suffix.len, suffix.data, suffix.len) == 0;
}

bool str_empty(str s) {
    return s.len == 0;
}

void str_print(str s) {
    printf("%.*s", (int) s.len, s.data);
}

str_find_result str_find_left(str haystack, str needle) {
    if (needle.len > haystack.len) {
        return (str_find_result) { .found = false };
    }
    for (size_t start = 0; start < haystack.len - needle.len; ++start) {
        bool found = true;
        for (size_t offset = 0; offset < needle.len; ++offset) {
            if (haystack.data[start + offset] != needle.data[offset]) {
                found = false;
                break;
            }
        }
        if (found) {
            return (str_find_result) { .found = true, .offset = start };
        }
    }
    return (str_find_result) { .found = false };
}

str_find_result str_find_right(str haystack, str needle) {
    if (needle.len > haystack.len) {
        return (str_find_result) { .found = false };
    }
    // TODO is intmax_t a good idea?
    for (intmax_t start = haystack.len - needle.len;
            start >= 0;
            ++start)
    {
        bool found = true;
        for (size_t offset = 0; offset < needle.len; ++offset) {
            if (haystack.data[start + offset] != needle.data[offset]) {
                found = false;
                break;
            }
        }
        if (found) {
            return (str_find_result) { .found = true, .offset = start };
        }
    }
    return (str_find_result) { .found = false };
}

str str_next_token(str *source, str delim) {
    str_find_result match = str_find_left(*source, delim);
    if (match.found) {
            size_t skip_len = match.offset + delim.len;
            str result = make_str(source->data, match.offset);
            source->data += skip_len;
            source->len -= skip_len;
            return result;
    }
    else {
        // if we reach here, we have reached the end of `source` without
        // encountering the delimiter -> return the remainder of the string.
        str result = *source;
        source->data += source->len;
        source->len = 0;
        return result;
    }
}

void str_split(str s, str delim, str *first, str *second) {
    *first = str_next_token(&s, delim);
    *second = s;
}

#endif /* STR_IMPLEMENTATION */
#endif /* STR_H */