// SPDX-License-Identifier: GPL-3.0-or-later
// Copyright 2025 YAMS Contributors

// Smoke test for path cache snapshot behavior via findDocumentByExactPath

#include <atomic>
#include <chrono>
#include <filesystem>
#include <thread>
#include <vector>

#include <catch2/catch_test_macros.hpp>

#include <yams/metadata/connection_pool.h>
#include <yams/metadata/metadata_repository.h>
#include <yams/metadata/path_utils.h>
#include <yams/storage/corpus_stats.h>

using namespace std::chrono;
using namespace yams::metadata;

namespace {

std::filesystem::path tempDbPath(const char* prefix) {
    const char* t = std::getenv("YAMS_TEST_TMPDIR");
    auto base = (t && *t) ? std::filesystem::path(t) : std::filesystem::temp_directory_path();
    std::error_code ec;
    std::filesystem::create_directories(base, ec);
    auto ts = std::chrono::steady_clock::now().time_since_epoch().count();
    auto p = base / (std::string(prefix) + std::to_string(ts) + ".db");
    std::filesystem::remove(p, ec);
    return p;
}

DocumentInfo mk(const std::string& path, const std::string& hash) {
    DocumentInfo d;
    d.filePath = path;
    auto derived = computePathDerivedValues(path);
    d.fileName = std::filesystem::path(derived.normalizedPath).filename().string();
    d.fileExtension = std::filesystem::path(d.fileName).extension().string();
    d.sha256Hash = hash;
    d.pathPrefix = derived.pathPrefix;
    d.reversePath = derived.reversePath;
    d.pathHash = derived.pathHash;
    d.parentHash = derived.parentHash;
    d.pathDepth = derived.pathDepth;
    auto now = floor<seconds>(system_clock::now());
    d.createdTime = d.modifiedTime = d.indexedTime = now;
    return d;
}

} // namespace

TEST_CASE("MetadataRepositoryCache: repeated exact path hits cache", "[unit][metadata][cache]") {
    auto dbPath = tempDbPath("repo_cache_catch2_");
    ConnectionPool pool(dbPath.string());
    REQUIRE(pool.initialize().has_value());
    MetadataRepository repo(pool);

    auto id = repo.insertDocument(mk("/cache/hit.md", "H1"));
    REQUIRE(id.has_value());

    // First call should populate cache
    auto first = repo.findDocumentByExactPath("/cache/hit.md");
    REQUIRE(first.has_value());
    REQUIRE(first.value().has_value());
    auto d1 = first.value().value();
    CHECK((d1.filePath == "/cache/hit.md"));

    // Second call should return same doc (served from cache path in repo)
    auto second = repo.findDocumentByExactPath("/cache/hit.md");
    REQUIRE(second.has_value());
    REQUIRE(second.value().has_value());
    auto d2 = second.value().value();
    CHECK((d2.filePath == d1.filePath));
    CHECK((d2.sha256Hash == d1.sha256Hash));

    // Cleanup
    pool.shutdown();
    std::error_code ec;
    std::filesystem::remove(dbPath, ec);
}

TEST_CASE("MetadataRepositoryCache: mutations invalidate cached path entries",
          "[unit][metadata][cache]") {
    auto dbPath = tempDbPath("repo_cache_invalidate_catch2_");
    ConnectionPool pool(dbPath.string());
    REQUIRE(pool.initialize().has_value());
    MetadataRepository repo(pool);

    constexpr int kDocs = 40; // > flush threshold (32) so entries land in the snapshot
    std::vector<int64_t> ids;
    for (int i = 0; i < kDocs; ++i) {
        auto path = "/cache/inv_" + std::to_string(i) + ".md";
        auto id = repo.insertDocument(mk(path, "H" + std::to_string(i)));
        REQUIRE(id.has_value());
        ids.push_back(id.value());
    }
    for (int i = 0; i < kDocs; ++i) {
        auto path = "/cache/inv_" + std::to_string(i) + ".md";
        auto found = repo.findDocumentByExactPath(path);
        REQUIRE(found.has_value());
        REQUIRE(found.value().has_value());
    }

    SECTION("deleteDocument removes the cached entry") {
        REQUIRE(repo.deleteDocument(ids[5]).has_value());
        auto after = repo.findDocumentByExactPath("/cache/inv_5.md");
        REQUIRE(after.has_value());
        CHECK_FALSE(after.value().has_value());
    }

    SECTION("updateDocument refreshes the cached entry") {
        auto current = repo.findDocumentByExactPath("/cache/inv_6.md");
        REQUIRE(current.has_value());
        REQUIRE(current.value().has_value());
        auto doc = current.value().value();
        doc.sha256Hash = "H6_updated";
        REQUIRE(repo.updateDocument(doc).has_value());

        auto after = repo.findDocumentByExactPath("/cache/inv_6.md");
        REQUIRE(after.has_value());
        REQUIRE(after.value().has_value());
        CHECK((after.value()->sha256Hash == "H6_updated"));
    }

    SECTION("rename invalidates the old path") {
        auto current = repo.findDocumentByExactPath("/cache/inv_7.md");
        REQUIRE(current.has_value());
        REQUIRE(current.value().has_value());
        auto doc = current.value().value();
        auto derived = computePathDerivedValues("/cache/renamed_7.md");
        doc.filePath = "/cache/renamed_7.md";
        doc.fileName = "renamed_7.md";
        doc.pathPrefix = derived.pathPrefix;
        doc.reversePath = derived.reversePath;
        doc.pathHash = derived.pathHash;
        doc.parentHash = derived.parentHash;
        doc.pathDepth = derived.pathDepth;
        REQUIRE(repo.updateDocument(doc).has_value());

        auto oldPath = repo.findDocumentByExactPath("/cache/inv_7.md");
        REQUIRE(oldPath.has_value());
        CHECK_FALSE(oldPath.value().has_value());

        auto newPath = repo.findDocumentByExactPath("/cache/renamed_7.md");
        REQUIRE(newPath.has_value());
        CHECK(newPath.value().has_value());
    }

    SECTION("deleteDocumentsBatch removes cached entries") {
        REQUIRE(repo.deleteDocumentsBatch({ids[8], ids[9]}).has_value());
        auto a = repo.findDocumentByExactPath("/cache/inv_8.md");
        REQUIRE(a.has_value());
        CHECK_FALSE(a.value().has_value());
        auto b = repo.findDocumentByExactPath("/cache/inv_9.md");
        REQUIRE(b.has_value());
        CHECK_FALSE(b.value().has_value());
    }

    pool.shutdown();
    std::error_code ec;
    std::filesystem::remove(dbPath, ec);
}

TEST_CASE("MetadataRepository: fresh instance over existing DB hydrates counters on first write",
          "[unit][metadata][counters]") {
    auto dbPath = tempDbPath("repo_counter_hydrate_catch2_");
    ConnectionPool pool(dbPath.string());
    REQUIRE(pool.initialize().has_value());

    std::vector<int64_t> ids;
    {
        MetadataRepository primary(pool);
        primary.initializeCounters();
        for (int i = 0; i < 3; ++i) {
            auto id = primary.insertDocument(
                mk("/counters/doc_" + std::to_string(i) + ".md", "CH" + std::to_string(i)));
            REQUIRE(id.has_value());
            ids.push_back(id.value());
        }
        REQUIRE(primary
                    .setMetadata(ids[0], "tag:primary", MetadataValue(std::string("true")))
                    .has_value());
    }

    // Second instance over the same DB, attached without initializeCounters()
    // — the stateless-CLI case. Tagging a previously untagged document bumps
    // docsWithTags by +1; the counters must be hydrated from the DB first or
    // the kv_ops invariant (docsWithTags <= docCount) fires against a
    // still-zero document count (previous behavior: SIGABRT).
    MetadataRepository fresh(pool);
    auto setRes = fresh.setMetadata(ids[1], "tag:fresh", MetadataValue(std::string("true")));
    REQUIRE(setRes.has_value());

    auto count = fresh.getDocumentCount();
    REQUIRE(count.has_value());
    CHECK(count.value() == 3);

    auto stats = fresh.getCorpusStats();
    REQUIRE(stats.has_value());
    CHECK(stats.value().docCount == 3);
    CHECK(stats.value().docsWithTags >= 1);
    CHECK(stats.value().docsWithTags <= stats.value().docCount);

    pool.shutdown();
    std::error_code ec;
    std::filesystem::remove(dbPath, ec);
}

TEST_CASE("MetadataRepositoryCache: concurrent exact path lookups stay coherent",
          "[unit][metadata][cache][concurrency]") {
    auto dbPath = tempDbPath("repo_cache_concurrent_catch2_");
    ConnectionPool pool(dbPath.string());
    REQUIRE(pool.initialize().has_value());
    MetadataRepository repo(pool);

    auto id = repo.insertDocument(mk("/cache/concurrent.md", "HC"));
    REQUIRE(id.has_value());

    std::atomic<bool> start{false};
    std::atomic<int> failures{0};
    std::vector<std::thread> threads;
    threads.reserve(8);

    for (int i = 0; i < 8; ++i) {
        threads.emplace_back([&]() {
            while (!start.load(std::memory_order_acquire)) {
                std::this_thread::yield();
            }
            for (int iter = 0; iter < 200; ++iter) {
                auto result = repo.findDocumentByExactPath("/cache/concurrent.md");
                if (!result || !result.value().has_value() || result.value()->sha256Hash != "HC") {
                    failures.fetch_add(1, std::memory_order_relaxed);
                }
            }
        });
    }

    start.store(true, std::memory_order_release);
    for (auto& thread : threads) {
        thread.join();
    }

    CHECK((failures.load(std::memory_order_relaxed) == 0));

    pool.shutdown();
    std::error_code ec;
    std::filesystem::remove(dbPath, ec);
}