#include "goal.h"

#include <ctype.h>
#include <stdlib.h>
#include <string.h>

static const char *const GOAL_PREAMBLE =
    "You are the reviewer for a terminal coding agent that is working toward a "
    "goal. You are given the goal — a success condition — and the agent's most "
    "recent reply. Decide whether the goal is fully met.\n"
    "\n"
    "Reply with exactly two lines:\n"
    "1. Either `MET` or `NOT MET` — your verdict.\n"
    "2. One short sentence: if met, what was accomplished; if not, the single "
    "most important gap to fix next.\n"
    "\n"
    "Be strict: the goal is met only when the stated success condition is "
    "clearly satisfied — not merely started, in progress, or partially done. "
    "Do not give the agent the benefit of the doubt, and do not add commentary "
    "beyond the two lines.";

void goal_spec_free(goal_spec *s)
{
    if (!s)
        return;
    free(s->criteria);
    s->criteria = NULL;
}

void goal_report_free(goal_report *r)
{
    if (!r)
        return;
    free(r->criteria);
    free(r);
}

const char *goal_evaluator_preamble(void)
{
    return GOAL_PREAMBLE;
}

static bool str_eq_i(const char *s, size_t n, const char *word)
{
    size_t wn = strlen(word);
    if (n != wn)
        return false;
    for (size_t i = 0; i < wn; i++) {
        char a = s[i], b = word[i];
        if (a >= 'a' && a <= 'z')
            a = (char)(a - 'a' + 'A');
        if (b >= 'a' && b <= 'z')
            b = (char)(b - 'a' + 'A');
        if (a != b)
            return false;
    }
    return true;
}

static int parse_tries(const char *s, size_t n, unsigned long *out, char **err)
{
    size_t tlen;
    const char *t = xtrim_span(s, n, &tlen);
    size_t digits = 0;
    while (digits < tlen && t[digits] >= '0' && t[digits] <= '9')
        digits++;
    if (digits == 0) {
        *err = xstrdup(
            "expected a number of tries after `stop after`, e.g. "
            "`stop after 5 tries`");
        return 0;
    }
    /* After the digits: end of input, or the word `tries` as a whole word.
     * "5xyz" is rejected; "5 tries" is the canonical form. */
    size_t rest = digits;
    while (rest < tlen && isspace((unsigned char)t[rest]))
        rest++;
    if (rest != tlen) {
        size_t wn = 5;
        bool word_ok = (tlen - rest) >= wn;
        if (word_ok) {
            const char *w = "tries";
            for (size_t i = 0; i < wn; i++) {
                char a = t[rest + i], b = w[i];
                if (a >= 'a' && a <= 'z')
                    a = (char)(a - 'a' + 'A');
                if (b >= 'a' && b <= 'z')
                    b = (char)(b - 'a' + 'A');
                if (a != b) {
                    word_ok = false;
                    break;
                }
            }
        }
        if (!word_ok || ((tlen - rest) > wn &&
                         isalpha((unsigned char)t[rest + wn]))) {
            *err = xstrdup(
                "expected a number of tries after `stop after`, e.g. "
                "`stop after 5 tries`");
            return 0;
        }
    }
    unsigned long value = 0;
    for (size_t i = 0; i < digits; i++) {
        value = value * 10UL + (unsigned long)(t[i] - '0');
        if (value > 4294967295UL) {
            *err = xstrdup(
                "expected a number of tries after `stop after`, e.g. "
                "`stop after 5 tries`");
            return 0;
        }
    }
    if (value == 0) {
        *err = xstrdup("the goal needs at least 1 try");
        return 0;
    }
    *out = value;
    return 1;
}

int goal_parse(const char *input, goal_spec *out, char **err)
{
    /* Zero on entry so a failed parse leaves a freeable, empty spec. */
    memset(out, 0, sizeof *out);
    const char *src = input ? input : "";
    size_t slen = strlen(src);
    size_t tlen;
    const char *t = xtrim_span(src, slen, &tlen);
    if (tlen == 0) {
        *err = xstrdup(
            "give the goal its success criteria, e.g. "
            "`/goal all tests pass, stop after 5 tries`");
        return 0;
    }

    const char marker[] = "stop after";
    size_t mlen = sizeof(marker) - 1;
    /* rfind: last occurrence of marker in [t, t+tlen). */
    const char *hit = NULL;
    const char *p = t;
    while (tlen - (size_t)(p - t) >= mlen) {
        void *m = memmem(p, tlen - (size_t)(p - t), marker, mlen);
        if (!m)
            break;
        hit = (const char* ) m;
        p = (const char *)m + 1;
    }

    if (!hit) {
        out->criteria = xstrndup(t, tlen);
        out->max_tries = GOAL_DEFAULT_MAX_TRIES;
        return 1;
    }

    size_t pre_len = (size_t)(hit - t);
    size_t clen;
    const char *crit = xtrim_span(t, pre_len, &clen);
    while (clen > 0 && crit[clen - 1] == ',')
        clen--;
    crit = xtrim_span(crit, clen, &clen);
    if (clen == 0) {
        *err = xstrdup(
            "give the goal its success criteria before `stop after`, e.g. "
            "`/goal all tests pass, stop after 5 tries`");
        return 0;
    }
    const char *tail = hit + mlen;
    if (!parse_tries(tail, tlen - (size_t)(tail - t), &out->max_tries, err))
        return 0;
    out->criteria = xstrndup(crit, clen);
    return 1;
}

char *goal_prompt(const goal_spec *spec, unsigned long attempt,
                  const char *feedback)
{
    const char *crit = spec->criteria ? spec->criteria : "";
    if (attempt <= 1)
        return xstrfmt(
            "Work toward this goal until it is fully met:\n\n%s\n\n"
            "Judge your own progress, verify it, and keep going if it is not "
            "done. When you are confident the goal is fully met, stop and say "
            "what you did.",
            crit);
    const char *fb = feedback ? feedback : "no specific feedback was given";
    return xstrfmt(
        "You are on attempt %lu of %lu toward this goal:\n\n%s\n\n"
        "A reviewer judged the goal NOT yet met: %s\n\n"
        "Address that gap and keep working. When you are confident the goal is "
        "fully met, stop and say what you did.",
        attempt, spec->max_tries, crit, fb);
}

/* True if `needle` occurs in `hay` as a whole word (A-Z only; `hay` is
 * already upper-cased). Prevents "MET" matching inside "UNMET". */
static bool has_word(const char *hay, const char *needle) {
    size_t nl = strlen(needle);
    const char *p = hay;
    while ((p = strstr(p, needle)) != NULL) {
        bool left_ok = (p == hay) || (p[-1] < 'A' || p[-1] > 'Z');
        bool right_ok = (p[nl] < 'A' || p[nl] > 'Z');
        if (left_ok && right_ok)
            return true;
        p += (nl > 0 ? nl : 1);
    }
    return false;
}

void goal_parse_verdict(const char *reply, goal_verdict *out)
{
    const char *src = reply ? reply : "";
    char *upper = xstrdup(src);
    for (char *c = upper; *c; c++)
        if (*c >= 'a' && *c <= 'z')
            *c = (char)(*c - 'a' + 'A');
    out->met = has_word(upper, "MET") && !has_word(upper, "NOT MET") &&
               !has_word(upper, "UNMET");
    free(upper);

    const char *chosen = NULL;
    size_t chosen_len = 0;
    const char *p = src;
    while (*p) {
        const char *nl = strchr(p, '\n');
        size_t linelen = nl ? (size_t)(nl - p) : strlen(p);
        size_t tlen;
            const char *line = xtrim_span(p, linelen, &tlen);
        if (tlen > 0 && !str_eq_i(line, tlen, "MET") &&
            !str_eq_i(line, tlen, "NOT MET")) {
            chosen = line;
            chosen_len = tlen;
            break;
        }
        if (!nl)
            break;
        p = nl + 1;
    }
    out->reason = chosen
                      ? xstrndup(chosen, chosen_len)
                      : xstrdup("the reviewer did not give a reason");
}