#include "store/sqlite.hpp"

#include <sqlite3.h>

#include <sys/stat.h>

#include <utility>

namespace velox::daemon::store {

// --- Db ------------------------------------------------------------------------------

Db::~Db() {
    if (db_ != nullptr) sqlite3_close(db_);
}

Db::Db(Db&& o) noexcept : db_(std::exchange(o.db_, nullptr)) {}

Db& Db::operator=(Db&& o) noexcept {
    if (this != &o) {
        if (db_ != nullptr) sqlite3_close(db_);
        db_ = std::exchange(o.db_, nullptr);
    }
    return *this;
}

DbError Db::last_error() const {
    return DbError{sqlite3_extended_errcode(db_), sqlite3_errmsg(db_)};
}

DbResult<Db> Db::open(const std::string& path) {
    sqlite3* handle = nullptr;
    const int rc = sqlite3_open_v2(
        path.c_str(), &handle, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_NOMUTEX,
        nullptr);
    if (rc != SQLITE_OK) {
        DbError e{rc, handle != nullptr ? sqlite3_errmsg(handle) : "sqlite3_open_v2 failed"};
        if (handle != nullptr) sqlite3_close(handle);
        return std::unexpected(std::move(e));
    }

    Db db(handle);
    // Not a secret store (credentials go to the Secret Service), but task URLs and pairing
    // hashes still are not world-readable. SQLite honours the umask; pin 0600 explicitly.
    if (path != ":memory:" && !path.empty() && path.front() != ':') {
        ::chmod(path.c_str(), 0600);
        ::chmod((path + "-wal").c_str(), 0600);
        ::chmod((path + "-shm").c_str(), 0600);
    }
    // WAL for crash-safe concurrent readers (docs/01 §1). busy_timeout so a writer waits
    // rather than returning SQLITE_BUSY under the RPC loop. foreign_keys is per-connection.
    for (const char* pragma : {"PRAGMA journal_mode=WAL", "PRAGMA synchronous=NORMAL",
                               "PRAGMA foreign_keys=ON", "PRAGMA busy_timeout=5000"}) {
        if (auto r = db.exec(pragma); !r) return std::unexpected(r.error());
    }
    return db;
}

DbResult<void> Db::exec(std::string_view sql) {
    char* err = nullptr;
    const int rc = sqlite3_exec(db_, std::string(sql).c_str(), nullptr, nullptr, &err);
    if (rc != SQLITE_OK) {
        DbError e{rc, err != nullptr ? err : sqlite3_errmsg(db_)};
        sqlite3_free(err);
        return std::unexpected(std::move(e));
    }
    return {};
}

DbResult<Stmt> Db::prepare(std::string_view sql) {
    sqlite3_stmt* s = nullptr;
    const int rc =
        sqlite3_prepare_v2(db_, sql.data(), static_cast<int>(sql.size()), &s, nullptr);
    if (rc != SQLITE_OK) return std::unexpected(last_error());
    return Stmt(db_, s);
}

std::int64_t Db::user_version() {
    auto st = prepare("PRAGMA user_version");
    if (!st) return -1;
    auto row = st->step();
    if (!row || !*row) return -1;
    return st->column_int(0);
}

DbResult<void> Db::set_user_version(std::int64_t v) {
    // PRAGMA does not accept a bound parameter; the value is our own integer.
    return exec("PRAGMA user_version=" + std::to_string(v));
}

// --- Stmt ----------------------------------------------------------------------------

Stmt::~Stmt() {
    if (stmt_ != nullptr) sqlite3_finalize(stmt_);
}

Stmt::Stmt(Stmt&& o) noexcept
    : db_(std::exchange(o.db_, nullptr)), stmt_(std::exchange(o.stmt_, nullptr)) {}

Stmt& Stmt::operator=(Stmt&& o) noexcept {
    if (this != &o) {
        if (stmt_ != nullptr) sqlite3_finalize(stmt_);
        db_ = std::exchange(o.db_, nullptr);
        stmt_ = std::exchange(o.stmt_, nullptr);
    }
    return *this;
}

DbError Stmt::last_error() const {
    return DbError{sqlite3_extended_errcode(db_), sqlite3_errmsg(db_)};
}

DbResult<void> Stmt::bind(int i, std::int64_t v) {
    if (sqlite3_bind_int64(stmt_, i, v) != SQLITE_OK) return std::unexpected(last_error());
    return {};
}

DbResult<void> Stmt::bind(int i, std::string_view v) {
    if (sqlite3_bind_text(stmt_, i, v.data(), static_cast<int>(v.size()), SQLITE_TRANSIENT) !=
        SQLITE_OK)
        return std::unexpected(last_error());
    return {};
}

DbResult<void> Stmt::bind_null(int i) {
    if (sqlite3_bind_null(stmt_, i) != SQLITE_OK) return std::unexpected(last_error());
    return {};
}

DbResult<bool> Stmt::step() {
    const int rc = sqlite3_step(stmt_);
    if (rc == SQLITE_ROW) return true;
    if (rc == SQLITE_DONE) return false;
    return std::unexpected(last_error());
}

DbResult<void> Stmt::reset() {
    if (sqlite3_reset(stmt_) != SQLITE_OK) return std::unexpected(last_error());
    return {};
}

std::int64_t Stmt::column_int(int i) const { return sqlite3_column_int64(stmt_, i); }

std::string Stmt::column_text(int i) const {
    const auto* p = sqlite3_column_text(stmt_, i);
    if (p == nullptr) return {};
    return std::string(reinterpret_cast<const char*>(p),
                       static_cast<std::size_t>(sqlite3_column_bytes(stmt_, i)));
}

bool Stmt::column_is_null(int i) const {
    return sqlite3_column_type(stmt_, i) == SQLITE_NULL;
}

}  // namespace velox::daemon::store