#include "amduat/fed/replay.h"

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

static int amduat_fed_octets_cmp(amduat_octets_t a, amduat_octets_t b) {
  size_t min_len;
  int cmp;

  min_len = a.len < b.len ? a.len : b.len;
  if (min_len > 0) {
    cmp = memcmp(a.data, b.data, min_len);
    if (cmp != 0) {
      return cmp;
    }
  }
  if (a.len < b.len) {
    return -1;
  }
  if (a.len > b.len) {
    return 1;
  }
  return 0;
}

static int amduat_fed_record_id_cmp(const amduat_fed_record_id_t *a,
                                    const amduat_fed_record_id_t *b) {
  if (a->type != b->type) {
    return (a->type < b->type) ? -1 : 1;
  }
  if (a->ref.hash_id != b->ref.hash_id) {
    return (a->ref.hash_id < b->ref.hash_id) ? -1 : 1;
  }
  return amduat_fed_octets_cmp(a->ref.digest, b->ref.digest);
}

static int amduat_fed_record_cmp(const void *lhs, const void *rhs) {
  const amduat_fed_record_t *a = (const amduat_fed_record_t *)lhs;
  const amduat_fed_record_t *b = (const amduat_fed_record_t *)rhs;

  if (a->logseq != b->logseq) {
    return (a->logseq < b->logseq) ? -1 : 1;
  }
  return amduat_fed_record_id_cmp(&a->id, &b->id);
}

static bool amduat_fed_record_clone(const amduat_fed_record_t *src,
                                    amduat_fed_record_t *out) {
  if (src == NULL || out == NULL) {
    return false;
  }
  *out = *src;
  if (!amduat_reference_clone(src->id.ref, &out->id.ref)) {
    return false;
  }
  if (!amduat_reference_clone(src->location.ref, &out->location.ref)) {
    amduat_reference_free(&out->id.ref);
    return false;
  }
  return true;
}

static void amduat_fed_record_free(amduat_fed_record_t *record) {
  if (record == NULL) {
    return;
  }
  amduat_reference_free(&record->id.ref);
  amduat_reference_free(&record->location.ref);
  memset(record, 0, sizeof(*record));
}

static bool amduat_fed_bounds_ok(const amduat_fed_record_t *record,
                                 uint64_t snapshot_id,
                                 uint64_t log_prefix) {
  if (record->snapshot_id < snapshot_id) {
    return true;
  }
  if (record->snapshot_id > snapshot_id) {
    return false;
  }
  return record->logseq <= log_prefix;
}

static bool amduat_fed_ref_eq(amduat_reference_t a, amduat_reference_t b) {
  return amduat_reference_eq(a, b);
}

static bool amduat_fed_tombstone_matches(const amduat_fed_record_t *tombstone,
                                         const amduat_fed_record_t *record) {
  if (tombstone->id.type != AMDUAT_FED_REC_TOMBSTONE) {
    return false;
  }
  if (record->id.type == AMDUAT_FED_REC_TOMBSTONE) {
    return false;
  }
  return amduat_fed_ref_eq(tombstone->id.ref, record->id.ref);
}

static bool amduat_fed_tombstone_list_has(
    const amduat_reference_t *refs,
    size_t refs_len,
    amduat_reference_t candidate) {
  size_t i;

  for (i = 0; i < refs_len; ++i) {
    if (amduat_fed_ref_eq(refs[i], candidate)) {
      return true;
    }
  }
  return false;
}

static bool amduat_fed_tombstone_list_push(amduat_reference_t **refs,
                                           size_t *len,
                                           size_t *cap,
                                           amduat_reference_t ref) {
  amduat_reference_t *next;

  if (*len == *cap) {
    size_t next_cap = (*cap == 0u) ? 4u : (*cap * 2u);
    next = (amduat_reference_t *)realloc(*refs,
                                         next_cap * sizeof(*next));
    if (next == NULL) {
      return false;
    }
    *refs = next;
    *cap = next_cap;
  }

  if (!amduat_reference_clone(ref, &(*refs)[*len])) {
    return false;
  }
  (*len)++;
  return true;
}

bool amduat_fed_record_validate(const amduat_fed_record_t *record) {
  if (record == NULL) {
    return false;
  }
  if (record->meta.visibility > 1u) {
    return false;
  }
  if (record->meta.has_source > 1u) {
    return false;
  }
  if (record->meta.has_source == 0u && record->meta.source_domain != 0u) {
    return false;
  }
  if (record->id.type < AMDUAT_FED_REC_ARTIFACT ||
      record->id.type > AMDUAT_FED_REC_TOMBSTONE) {
    return false;
  }
  if (record->id.ref.digest.len != 0u &&
      record->id.ref.digest.data == NULL) {
    return false;
  }
  if (record->location.ref.digest.len != 0u &&
      record->location.ref.digest.data == NULL) {
    return false;
  }
  return true;
}

bool amduat_fed_replay_domain(const amduat_fed_record_t *records,
                              size_t count,
                              uint32_t domain_id,
                              uint64_t snapshot_id,
                              uint64_t log_prefix,
                              amduat_fed_replay_view_t *out_view) {
  amduat_fed_record_t *scratch;
  amduat_reference_t *tombstones;
  size_t tombstones_len;
  size_t tombstones_cap;
  size_t scratch_len;
  size_t i;
  size_t out_len;
  bool ok;

  if (out_view == NULL) {
    return false;
  }
  out_view->records = NULL;
  out_view->len = 0;

  if (records == NULL && count != 0u) {
    return false;
  }

  if (count == 0u) {
    return true;
  }

  scratch = (amduat_fed_record_t *)calloc(count, sizeof(*scratch));
  if (scratch == NULL) {
    return false;
  }
  tombstones = NULL;
  tombstones_len = 0;
  tombstones_cap = 0;

  scratch_len = 0;
  for (i = 0; i < count; ++i) {
    const amduat_fed_record_t *record = &records[i];

    if (record->meta.domain_id != domain_id) {
      continue;
    }
    if (!amduat_fed_record_validate(record)) {
      continue;
    }
    if (!amduat_fed_bounds_ok(record, snapshot_id, log_prefix)) {
      continue;
    }
    if (!amduat_fed_record_clone(record, &scratch[scratch_len])) {
      while (scratch_len > 0) {
        scratch_len--;
        amduat_fed_record_free(&scratch[scratch_len]);
      }
      free(scratch);
      return false;
    }
    scratch_len++;
  }

  qsort(scratch, scratch_len, sizeof(*scratch), amduat_fed_record_cmp);

  ok = true;
  out_len = 0;
  for (i = 0; i < scratch_len; ++i) {
    amduat_fed_record_t current = scratch[i];
    size_t j;
    bool tombstoned;

    scratch[i].id.ref.digest.data = NULL;
    scratch[i].id.ref.digest.len = 0u;

    if (current.id.type == AMDUAT_FED_REC_TOMBSTONE) {
      for (j = 0; j < out_len; ++j) {
        if (amduat_fed_tombstone_matches(&current, &scratch[j])) {
          amduat_fed_record_free(&scratch[j]);
          memmove(&scratch[j],
                  &scratch[j + 1],
                  (out_len - j - 1) * sizeof(*scratch));
          out_len--;
          j--;
        }
      }
      if (!amduat_fed_tombstone_list_push(&tombstones,
                                          &tombstones_len,
                                          &tombstones_cap,
                                          current.id.ref)) {
        amduat_fed_record_free(&current);
        ok = false;
        break;
      }
      amduat_fed_record_free(&current);
      continue;
    }

    tombstoned = amduat_fed_tombstone_list_has(tombstones,
                                               tombstones_len,
                                               current.id.ref);
    if (tombstoned) {
      amduat_fed_record_free(&current);
      continue;
    }

    scratch[out_len++] = current;
  }

  for (i = 0; i < tombstones_len; ++i) {
    amduat_reference_free(&tombstones[i]);
  }
  free(tombstones);

  if (!ok) {
    for (i = 0; i < scratch_len; ++i) {
      amduat_fed_record_free(&scratch[i]);
    }
    free(scratch);
    return false;
  }

  out_view->records = scratch;
  out_view->len = out_len;
  return true;
}

void amduat_fed_replay_view_free(amduat_fed_replay_view_t *view) {
  size_t i;

  if (view == NULL) {
    return;
  }
  if (view->records != NULL) {
    for (i = 0; i < view->len; ++i) {
      amduat_fed_record_free(&view->records[i]);
    }
    free(view->records);
  }
  view->records = NULL;
  view->len = 0;
}