/*
 * test_trace_equivalence_cmp.c - the comparisons of the decision-trace
 * equivalence test (test_trace_equivalence.c, which documents what is
 * compared and why; scheduler-sim-decision-trace task 6.3): texts,
 * .replay files apart from the header's wall-clock field, and the decoded
 * recorded sessions (decisions, allocations, pend reasons). Each returns
 * NULL when equal, else a malloc'd description of the first difference.
 * Kept apart from the scenarios for the 800-line file cap.
 */
#include <limits.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <unity/unity.h>

#include "controller.capnp.h"
#include "preason.h"
#include "recording.h"
#include "scheduler.h"

#include "test_repl_trace_e2e.h"
#include "test_trace_equivalence.h"

extern int msg_root_has_shape(struct capn* c, capn_ptr* out,
                              size_t want_words, size_t want_ptrs);

/* ---------------------------------------------------------------------- */
/* Comparisons: each returns NULL when equal, else a description            */
/* ---------------------------------------------------------------------- */

static char* describe(const char* fmt, ...)
    __attribute__((format(printf, 1, 2)));

static char* describe(const char* fmt, ...)
{
    char*   out = (char*)malloc(1024);
    va_list ap;

    TEST_ASSERT_NOT_NULL(out);
    va_start(ap, fmt);
    vsnprintf(out, 1024, fmt, ap);
    va_end(ap);
    return out;
}

/* First differing line of two texts. */
char* text_diff(const char* a, const char* b)
{
    long i    = 0;
    long line = 1;
    long bol  = 0;

    while ((a[i] != '\0') && (a[i] == b[i])) {
        if (a[i] == '\n') {
            line++;
            bol = i + 1;
        }
        i++;
    }
    if (a[i] == b[i]) {
        return NULL;
    }
    return describe("line %ld:\n  off:    %.*s\n  traced: %.*s", line,
                    (int)strcspn(a + bol, "\n"), a + bol,
                    (int)strcspn(b + bol, "\n"), b + bol);
}

/* A recording (or snapshot) header without recordingStartWall, and the
 * offset just past it. */
static void read_header(const char* path, replay_header_t* hdr, long* end)
{
    FILE*               f = fopen(path, "rb");
    struct capn         c;
    struct ReplayHeader wire;
    ReplayHeader_ptr    p;

    TEST_ASSERT_NOT_NULL_MESSAGE(f, path);
    TEST_ASSERT_EQUAL_INT(0, capn_init_fp(&c, f, 0));
    p.p = capn_getp(capn_root(&c), 0, 1);
    read_ReplayHeader(&wire, p);
    memset(hdr, 0, sizeof(*hdr));
    decode_ReplayHeader(hdr, &wire);
    capn_free(&c);
    *end = ftell(f);
    fclose(f);
}

static bool same_str(const char* a, const char* b)
{
    return (a == b) || ((a != NULL) && (b != NULL) && (strcmp(a, b) == 0));
}

/* Byte comparison of two .replay files apart from recordingStartWall. */
char* recording_diff(const char* a_path, const char* b_path)
{
    replay_header_t ha;
    replay_header_t hb;
    long            ea;
    long            eb;
    long            la;
    long            lb;
    char*           a = slurp(a_path, &la);
    char*           b = slurp(b_path, &lb);
    char*           why = NULL;
    long            i;

    TEST_ASSERT_NOT_NULL_MESSAGE(a, a_path);
    TEST_ASSERT_NOT_NULL_MESSAGE(b, b_path);
    read_header(a_path, &ha, &ea);
    read_header(b_path, &hb, &eb);
    if (!same_str(ha.recorder_version, hb.recorder_version)
        || (ha.recording_start_ts != hb.recording_start_ts)
        || !same_str(ha.sched_policy, hb.sched_policy)
        || (ha.cluster != NULL) || (hb.cluster != NULL)) {
        why = describe("header fields differ");
    } else if ((la - ea) != (lb - eb)) {
        why = describe("length after the header: %ld != %ld", la - ea,
                       lb - eb);
    } else {
        for (i = 0; (i < la - ea) && (a[ea + i] == b[eb + i]); i++) {
        }
        if (i < la - ea) {
            why = describe("byte %ld after the header differs", i);
        }
    }
    free_ReplayHeader(&ha);
    free_ReplayHeader(&hb);
    free(a);
    free(b);
    return why;
}

/* ---------------------------------------------------------------------- */
/* Decoded decisions                                                        */
/* ---------------------------------------------------------------------- */

void sessions_read(const char* path, sessions_t* out)
{
    FILE*       f = fopen(path, "rb");
    struct capn c;
    int         msg = 0;

    memset(out, 0, sizeof(*out));
    TEST_ASSERT_NOT_NULL_MESSAGE(f, path);
    while (capn_init_fp(&c, f, 0) == 0) {
        capn_ptr root;

        if ((msg++ > 0)
            && msg_root_has_shape(&c, &root, ReplaySession_word_count,
                                  ReplaySession_pointer_count)) {
            ReplaySession_ptr sp;
            replay_session_t* s = NULL;
            int               i;

            sp.p = root;
            decode_ReplaySession_ptr(&s, sp);
            TEST_ASSERT_NOT_NULL(s);
            out->s = (replay_session_t**)realloc(
                out->s, sizeof(*out->s) * (size_t)(out->n + 1));
            TEST_ASSERT_NOT_NULL(out->s);
            out->s[out->n++] = s;
            for (i = 0; i < s->n_decisions; i++) {
                replay_decision_t* d = s->decisions[i];

                if (d->body_which == ReplayDecision_body_dispatch) {
                    out->ndispatch++;
                } else if (d->body_which == ReplayDecision_body_pend) {
                    xce_job_preason_t* pr = d->body.pend->reason;

                    out->npend++;
                    if ((pr != NULL)
                        && ((pr->nhost_reasons + pr->nres_reasons) > 0)) {
                        out->npend_detail++;
                    }
                }
            }
        }
        capn_free(&c);
    }
    fclose(f);
}

void sessions_free(sessions_t* s)
{
    int i;

    for (i = 0; i < s->n; i++) {
        free_ReplaySession_ptr(&(s->s[i]));
    }
    free(s->s);
    memset(s, 0, sizeof(*s));
}

static char* alloc_diff(const xce_job_alloc_t* a, const xce_job_alloc_t* b)
{
    int h;

    if ((a == NULL) || (b == NULL)) {
        return (a == b) ? NULL : describe("alloc NULL on one side");
    }
    if ((a->jobid != b->jobid) || (a->nhosts != b->nhosts)
        || (a->nres_shared != b->nres_shared)) {
        return describe("dispatch %llu: nhosts %d/%d, nres_shared %d/%d",
                        (unsigned long long)a->jobid, a->nhosts, b->nhosts,
                        a->nres_shared, b->nres_shared);
    }
    for (h = 0; h < a->nhosts; h++) {
        if (!same_str(a->allocs[h]->host, b->allocs[h]->host)
            || (a->allocs[h]->nallocs != b->allocs[h]->nallocs)) {
            return describe("dispatch %llu: host %d differs",
                            (unsigned long long)a->jobid, h);
        }
    }
    return NULL;
}

static char* decision_diff(const replay_decision_t* a,
                           const replay_decision_t* b)
{
    char* why = NULL;

    if ((a->ts != b->ts) || (a->body_which != b->body_which)) {
        return describe("ts %llu/%llu, op %d/%d", (unsigned long long)a->ts,
                        (unsigned long long)b->ts, a->body_which,
                        b->body_which);
    }
    if (a->body_which == ReplayDecision_body_dispatch) {
        return alloc_diff(a->body.dispatch->alloc, b->body.dispatch->alloc);
    }
    if (a->body_which == ReplayDecision_body_pend) {
        if (a->body.pend->jobid != b->body.pend->jobid) {
            return describe("pend jobid %llu/%llu",
                            (unsigned long long)a->body.pend->jobid,
                            (unsigned long long)b->body.pend->jobid);
        }
        if (!job_preason_eq(a->body.pend->reason, b->body.pend->reason,
                            &why)) {
            char* out = describe("pend %llu reason: %s",
                                 (unsigned long long)a->body.pend->jobid,
                                 (why != NULL) ? why : "?");

            free(why);
            return out;
        }
    }
    return NULL;
}

char* sessions_diff(const sessions_t* a, const sessions_t* b)
{
    int i;
    int j;

    if (a->n != b->n) {
        return describe("session count %d != %d", a->n, b->n);
    }
    for (i = 0; i < a->n; i++) {
        if ((a->s[i]->begin_round != b->s[i]->begin_round)
            || (a->s[i]->n_decisions != b->s[i]->n_decisions)) {
            return describe("session %d: round %llu/%llu, %d/%d decisions",
                            i, (unsigned long long)a->s[i]->begin_round,
                            (unsigned long long)b->s[i]->begin_round,
                            a->s[i]->n_decisions, b->s[i]->n_decisions);
        }
        for (j = 0; j < a->s[i]->n_decisions; j++) {
            char* why = decision_diff(a->s[i]->decisions[j],
                                      b->s[i]->decisions[j]);

            if (why != NULL) {
                char* out = describe("session %d decision %d: %s", i, j, why);

                free(why);
                return out;
            }
        }
    }
    return NULL;
}