#include "pms_match.h"
#include "pms_data.h"
#include "pms_util.h"
#include <limits.h>
#include <stdbool.h>
#include <stddef.h>

static bool verse_matches(const pms_ref *ref, const pms_verse *v) {
    switch (ref->type) {
    case PMS_REF_SEARCH: {
        if (ref->book != 0 && (unsigned int)v->book != ref->book) {
            return false;
        }
        if (ref->chapter != 0 && (unsigned int)v->chapter != ref->chapter) {
            return false;
        }
        char folded[4096];
        pms_fold_utf8(v->text, folded, sizeof(folded), NULL);
        return regexec(&ref->search, folded, 0, NULL, 0) == 0;
    }

    case PMS_REF_EXACT:
        return (unsigned int)v->book == ref->book &&
               (ref->chapter == 0 || (unsigned int)v->chapter == ref->chapter) &&
               (ref->verse == 0 || (unsigned int)v->verse == ref->verse);

    case PMS_REF_EXACT_SET:
        if ((unsigned int)v->book != ref->book || (unsigned int)v->chapter != ref->chapter) {
            return false;
        }
        for (int i = 0; i < ref->verse_set_count; i++) {
            if ((unsigned int)v->verse == ref->verse_set[i]) {
                return true;
            }
        }
        return false;

    case PMS_REF_RANGE:
        return (unsigned int)v->book == ref->book &&
               ((ref->chapter_end == 0 && (unsigned int)v->chapter == ref->chapter) ||
                ((unsigned int)v->chapter >= ref->chapter && (unsigned int)v->chapter <= ref->chapter_end)) &&
               (ref->verse == 0 || (unsigned int)v->verse >= ref->verse) &&
               (ref->verse_end == 0 || (unsigned int)v->verse <= ref->verse_end);

    case PMS_REF_RANGE_EXT:
        return (unsigned int)v->book == ref->book &&
               (((unsigned int)v->chapter == ref->chapter && (unsigned int)v->verse >= ref->verse && ref->chapter != ref->chapter_end) ||
                ((unsigned int)v->chapter > ref->chapter && (unsigned int)v->chapter < ref->chapter_end) ||
                ((unsigned int)v->chapter == ref->chapter_end && (unsigned int)v->verse <= ref->verse_end && ref->chapter != ref->chapter_end) ||
                (ref->chapter == ref->chapter_end && (unsigned int)v->chapter == ref->chapter &&
                 (unsigned int)v->verse >= ref->verse && (unsigned int)v->verse <= ref->verse_end));

    default:
        return false;
    }
}

static pms_range chapter_bounds(int i, const pms_config *config) {
    pms_range bounds = {.start = i, .end = i + 1};
    int book = pms_verses[i].book;
    int chapter = pms_verses[i].chapter;

    int max_before = config->chapter_context ? INT_MAX : config->before_context;
    for (int n = 0; n < max_before && bounds.start > 0; n++) {
        if (pms_verses[bounds.start - 1].book == book &&
            (!config->chapter_context || pms_verses[bounds.start - 1].chapter == chapter)) {
            bounds.start--;
        } else {
            break;
        }
    }

    int max_after = config->chapter_context ? INT_MAX : config->after_context;
    for (int n = 0; n < max_after && bounds.end < pms_verses_length; n++) {
        if (pms_verses[bounds.end].book == book &&
            (!config->chapter_context || pms_verses[bounds.end].chapter == chapter)) {
            bounds.end++;
        } else {
            break;
        }
    }

    return bounds;
}

static int find_next_match(const pms_ref *ref, const pms_config *config, int i, pms_range *range) {
    for (; i < pms_verses_length; i++) {
        if (verse_matches(ref, &pms_verses[i])) {
            *range = chapter_bounds(i, config);
            return i;
        }
    }
    return -1;
}

int pms_next_verse(const pms_ref *ref, const pms_config *config, pms_match_data *data) {
    if (data->current >= pms_verses_length) {
        return -1;
    }

    if (data->current == 0 && data->next_match == 0) {
        data->matches[0] = (pms_range){-1, -1};
        data->matches[1] = (pms_range){-1, -1};

        data->next_match = find_next_match(ref, config, 0, &data->matches[0]);
        if (data->next_match < 0) {
            data->current = pms_verses_length;
            return -1;
        }
        data->next_match = find_next_match(ref, config, data->next_match + 1, &data->matches[1]);
    }

    while (data->matches[1].start != -1 && data->matches[1].start <= data->matches[0].end) {
        if (data->matches[1].end > data->matches[0].end) {
            data->matches[0].end = data->matches[1].end;
        }
        data->matches[1] = (pms_range){-1, -1};
        if (data->next_match >= 0) {
            data->next_match = find_next_match(ref, config, data->next_match + 1, &data->matches[1]);
        }
    }

    if (data->current < data->matches[0].start) {
        data->current = data->matches[0].start;
    }

    if (data->current < data->matches[0].end) {
        return data->current++;
    }

    if (data->matches[1].start != -1) {
        data->matches[0] = data->matches[1];
        data->matches[1] = (pms_range){-1, -1};
        if (data->next_match >= 0) {
            data->next_match = find_next_match(ref, config, data->next_match + 1, &data->matches[1]);
        }
        return pms_next_verse(ref, config, data);
    }

    data->current = pms_verses_length;
    return -1;
}