/**
 * Unit tests for per-collection timestamp precision (v1.6.0 Task 7).
 *
 * Exercises MemoryStore + CollectionConfigManager directly — no gRPC server.
 *
 * Test cases:
 *   1. ms is the default precision
 *   2. ns yields unique timestamps in a tight 1000-doc insert loop
 *   3. ms stamps fit in the ms range (< 10^15) over 1000 docs
 *   4. setConfig() is idempotent
 *   5. configFor() reflects setConfig() immediately (no reload required)
 *   6. Unknown collections return the default config
 */

#include "../service/src/memory_store.hpp"
#include "../service/src/config/collection_config_manager.hpp"
#include "../service/src/document.hpp"

#include <cassert>
#include <cstdint>
#include <iostream>
#include <nlohmann/json.hpp>
#include <set>
#include <string>

using smartbotic::database::CollectionCfg;
using smartbotic::database::CollectionConfigManager;
using smartbotic::database::CollectionOptions;
using smartbotic::database::Document;
using smartbotic::database::MemoryStore;

namespace {

// Anything below 10^15 fits comfortably in the ms-since-epoch range (≈ 2001..),
// anything above is unambiguously ns-since-epoch in the current era.
constexpr uint64_t NS_THRESHOLD = 1'000'000'000'000'000ULL;  // 10^15

MemoryStore::Config defaultConfig() {
    MemoryStore::Config cfg;
    cfg.nodeId = "test";
    cfg.maxMemoryBytes = 256ULL * 1024 * 1024;
    return cfg;
}

Document makeDoc(const std::string& id = "") {
    Document d;
    if (!id.empty()) d.id = id;
    d.set_data(nlohmann::json{{"value", "x"}});
    return d;
}

} // anonymous namespace

void test_default_is_ms() {
    MemoryStore store(defaultConfig());
    store.start();
    CollectionConfigManager mgr(store);
    store.setConfigManager(&mgr);

    store.createCollection("docs_default", CollectionOptions{});

    auto id = store.insert("docs_default", makeDoc());
    auto doc = store.get("docs_default", id);
    assert(doc.has_value());
    assert(doc->createdAt > 0);
    assert(doc->createdAt < NS_THRESHOLD);  // ms range
    assert(doc->updatedAt > 0);
    assert(doc->updatedAt < NS_THRESHOLD);

    store.stop();
    std::cout << "PASS: default precision is ms (createdAt=" << doc->createdAt << ")\n";
}

void test_ns_yields_unique_timestamps_in_tight_loop() {
    MemoryStore store(defaultConfig());
    store.start();
    CollectionConfigManager mgr(store);
    store.setConfigManager(&mgr);

    store.createCollection("docs_ns", CollectionOptions{});

    CollectionCfg ns_cfg;
    ns_cfg.timestampPrecision = "ns";
    std::string err;
    bool ok = mgr.setConfig("docs_ns", ns_cfg, err);
    assert(ok);

    std::set<uint64_t> seen;
    constexpr int N = 1000;
    for (int i = 0; i < N; ++i) {
        auto id = store.insert("docs_ns", makeDoc());
        auto doc = store.get("docs_ns", id);
        assert(doc.has_value());
        assert(doc->createdAt >= NS_THRESHOLD);  // ns range
        auto [it, inserted] = seen.insert(doc->createdAt);
        assert(inserted);  // every timestamp must be unique
    }
    assert(seen.size() == static_cast<size_t>(N));

    store.stop();
    std::cout << "PASS: ns precision produces " << N
              << " unique timestamps in tight loop\n";
}

void test_ms_baseline_fits_in_ms_range() {
    MemoryStore store(defaultConfig());
    store.start();
    CollectionConfigManager mgr(store);
    store.setConfigManager(&mgr);

    store.createCollection("docs_ms", CollectionOptions{});

    CollectionCfg ms_cfg;
    ms_cfg.timestampPrecision = "ms";
    std::string err;
    bool ok = mgr.setConfig("docs_ms", ms_cfg, err);
    assert(ok);

    constexpr int N = 1000;
    for (int i = 0; i < N; ++i) {
        auto id = store.insert("docs_ms", makeDoc());
        auto doc = store.get("docs_ms", id);
        assert(doc.has_value());
        assert(doc->createdAt < NS_THRESHOLD);  // ms range
    }
    // We deliberately do NOT assert on tie-production here — it's machine-
    // dependent. The invariant that ms-stamped docs stay in the ms range is
    // what the default-preservation story needs.

    store.stop();
    std::cout << "PASS: ms precision stamps fit in ms range (" << N << " docs)\n";
}

void test_idempotent_configure() {
    MemoryStore store(defaultConfig());
    store.start();
    CollectionConfigManager mgr(store);
    store.setConfigManager(&mgr);

    CollectionCfg cfg;
    cfg.timestampPrecision = "ns";
    std::string err;

    assert(mgr.setConfig("docs_idem", cfg, err));
    assert(mgr.configFor("docs_idem").timestampPrecision == "ns");
    assert(mgr.hasExplicitConfig("docs_idem"));

    // Second call with the same value — should succeed and leave state intact.
    assert(mgr.setConfig("docs_idem", cfg, err));
    assert(mgr.configFor("docs_idem").timestampPrecision == "ns");
    assert(mgr.hasExplicitConfig("docs_idem"));

    store.stop();
    std::cout << "PASS: setConfig is idempotent\n";
}

void test_cache_reflects_configure_immediately() {
    MemoryStore store(defaultConfig());
    store.start();
    CollectionConfigManager mgr(store);
    store.setConfigManager(&mgr);

    // Before configure: default ms, not explicit.
    assert(mgr.configFor("docs_cache").timestampPrecision == "ms");
    assert(!mgr.hasExplicitConfig("docs_cache"));

    CollectionCfg cfg;
    cfg.timestampPrecision = "ns";
    std::string err;
    assert(mgr.setConfig("docs_cache", cfg, err));

    // After configure: ns, immediately — no reloadFromStore() required.
    assert(mgr.configFor("docs_cache").timestampPrecision == "ns");
    assert(mgr.hasExplicitConfig("docs_cache"));

    store.stop();
    std::cout << "PASS: cache reflects setConfig immediately\n";
}

void test_default_for_unknown_collection() {
    MemoryStore store(defaultConfig());
    store.start();
    CollectionConfigManager mgr(store);
    store.setConfigManager(&mgr);

    auto cfg = mgr.configFor("never_configured_collection");
    assert(cfg.timestampPrecision == "ms");
    assert(!mgr.hasExplicitConfig("never_configured_collection"));

    store.stop();
    std::cout << "PASS: default config returned for unknown collection\n";
}

int main() {
    test_default_is_ms();
    test_ns_yields_unique_timestamps_in_tight_loop();
    test_ms_baseline_fits_in_ms_range();
    test_idempotent_configure();
    test_cache_reflects_configure_immediately();
    test_default_for_unknown_collection();
    std::cout << "\nAll timestamp precision tests PASSED!\n";
    return 0;
}