#include "db.h"

#ifdef VOICECAT_HAS_NET

#include <chrono>
#include <cstring>
#include <stdexcept>

#include <sodium.h>
#include <sqlite3.h>

namespace voicecat::server {

// ── Schema ────────────────────────────────────────────────────────────────────

static constexpr const char* kCreateSchema = R"sql(
CREATE TABLE IF NOT EXISTS accounts (
    id         INTEGER PRIMARY KEY AUTOINCREMENT,
    username   TEXT    UNIQUE NOT NULL,
    pw_hash    TEXT    NOT NULL,
    is_admin   INTEGER NOT NULL DEFAULT 0,
    created_at INTEGER NOT NULL,
    last_login INTEGER NOT NULL DEFAULT 0
);
CREATE TABLE IF NOT EXISTS server_meta (
    key   TEXT PRIMARY KEY,
    value TEXT NOT NULL
);
INSERT OR IGNORE INTO server_meta (key, value) VALUES ('schema_version', '1');
)sql";

// ── Database ──────────────────────────────────────────────────────────────────

Database::Database(std::string path) : path_(std::move(path)) {}

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

bool Database::open(std::string& error) {
    int rc = sqlite3_open(path_.c_str(), &db_);
    if (rc != SQLITE_OK) {
        error = sqlite3_errmsg(db_);
        sqlite3_close(db_);
        db_ = nullptr;
        return false;
    }
    sqlite3_busy_timeout(db_, 5000);
    // WAL mode for concurrency
    exec("PRAGMA journal_mode=WAL", error);
    exec("PRAGMA synchronous=NORMAL", error);
    error.clear();
    if (!exec(kCreateSchema, error)) return false;
    return true;
}

bool Database::is_empty() {
    sqlite3_stmt* stmt = nullptr;
    sqlite3_prepare_v2(db_, "SELECT COUNT(*) FROM accounts", -1, &stmt, nullptr);
    int count = 0;
    if (sqlite3_step(stmt) == SQLITE_ROW) count = sqlite3_column_int(stmt, 0);
    sqlite3_finalize(stmt);
    return count == 0;
}

std::optional<Account> Database::create_account(const std::string& username,
                                                  const std::string& password,
                                                  bool is_admin, std::string& error) {
    if (username.empty() || password.empty()) {
        error = "username and password must not be empty";
        return std::nullopt;
    }
    // Hash with Argon2id via libsodium
    char hash[crypto_pwhash_STRBYTES];
    if (crypto_pwhash_str(hash, password.c_str(), password.size(),
                           crypto_pwhash_OPSLIMIT_INTERACTIVE,
                           crypto_pwhash_MEMLIMIT_INTERACTIVE) != 0) {
        error = "Argon2id hashing failed (OOM?)";
        return std::nullopt;
    }

    int64_t now = now_unix();
    sqlite3_stmt* stmt = nullptr;
    int rc = sqlite3_prepare_v2(db_,
        "INSERT INTO accounts (username, pw_hash, is_admin, created_at) VALUES (?,?,?,?)",
        -1, &stmt, nullptr);
    if (rc != SQLITE_OK) { error = sqlite3_errmsg(db_); return std::nullopt; }

    sqlite3_bind_text(stmt, 1, username.c_str(), -1, SQLITE_TRANSIENT);
    sqlite3_bind_text(stmt, 2, hash, -1, SQLITE_TRANSIENT);
    sqlite3_bind_int(stmt, 3, is_admin ? 1 : 0);
    sqlite3_bind_int64(stmt, 4, now);
    rc = sqlite3_step(stmt);
    sqlite3_finalize(stmt);

    if (rc != SQLITE_DONE) {
        error = sqlite3_errmsg(db_);
        return std::nullopt;
    }

    Account acc;
    acc.id         = sqlite3_last_insert_rowid(db_);
    acc.username   = username;
    acc.is_admin   = is_admin;
    acc.created_at = now;
    return acc;
}

bool Database::reset_password(const std::string& username, const std::string& new_password,
                               std::string& error) {
    char hash[crypto_pwhash_STRBYTES];
    if (crypto_pwhash_str(hash, new_password.c_str(), new_password.size(),
                           crypto_pwhash_OPSLIMIT_INTERACTIVE,
                           crypto_pwhash_MEMLIMIT_INTERACTIVE) != 0) {
        error = "Argon2id hashing failed";
        return false;
    }
    sqlite3_stmt* stmt = nullptr;
    sqlite3_prepare_v2(db_, "UPDATE accounts SET pw_hash=? WHERE username=?", -1, &stmt, nullptr);
    sqlite3_bind_text(stmt, 1, hash, -1, SQLITE_TRANSIENT);
    sqlite3_bind_text(stmt, 2, username.c_str(), -1, SQLITE_TRANSIENT);
    int rc = sqlite3_step(stmt);
    sqlite3_finalize(stmt);
    if (rc != SQLITE_DONE) { error = sqlite3_errmsg(db_); return false; }
    if (sqlite3_changes(db_) == 0) { error = "user not found: " + username; return false; }
    return true;
}

bool Database::delete_account(const std::string& username, std::string& error) {
    sqlite3_stmt* stmt = nullptr;
    sqlite3_prepare_v2(db_, "DELETE FROM accounts WHERE username=?", -1, &stmt, nullptr);
    sqlite3_bind_text(stmt, 1, username.c_str(), -1, SQLITE_TRANSIENT);
    int rc = sqlite3_step(stmt);
    sqlite3_finalize(stmt);
    if (rc != SQLITE_DONE) { error = sqlite3_errmsg(db_); return false; }
    if (sqlite3_changes(db_) == 0) { error = "user not found: " + username; return false; }
    return true;
}

std::vector<Account> Database::list_accounts() {
    std::vector<Account> result;
    sqlite3_stmt* stmt = nullptr;
    sqlite3_prepare_v2(db_,
        "SELECT id, username, is_admin, created_at, last_login FROM accounts ORDER BY username",
        -1, &stmt, nullptr);
    while (sqlite3_step(stmt) == SQLITE_ROW) {
        Account acc;
        acc.id         = sqlite3_column_int64(stmt, 0);
        acc.username   = reinterpret_cast<const char*>(sqlite3_column_text(stmt, 1));
        acc.is_admin   = sqlite3_column_int(stmt, 2) != 0;
        acc.created_at = sqlite3_column_int64(stmt, 3);
        acc.last_login = sqlite3_column_int64(stmt, 4);
        result.push_back(acc);
    }
    sqlite3_finalize(stmt);
    return result;
}

std::optional<Account> Database::authenticate(const std::string& username,
                                               const std::string& password) {
    sqlite3_stmt* stmt = nullptr;
    sqlite3_prepare_v2(db_,
        "SELECT id, pw_hash, is_admin, created_at, last_login FROM accounts WHERE username=?",
        -1, &stmt, nullptr);
    sqlite3_bind_text(stmt, 1, username.c_str(), -1, SQLITE_TRANSIENT);
    int rc = sqlite3_step(stmt);
    if (rc != SQLITE_ROW) { sqlite3_finalize(stmt); return std::nullopt; }

    int64_t id       = sqlite3_column_int64(stmt, 0);
    std::string hash = reinterpret_cast<const char*>(sqlite3_column_text(stmt, 1));
    bool is_admin    = sqlite3_column_int(stmt, 2) != 0;
    int64_t created  = sqlite3_column_int64(stmt, 3);
    sqlite3_finalize(stmt);

    // Verify Argon2id — deliberately slow
    if (crypto_pwhash_str_verify(hash.c_str(), password.c_str(), password.size()) != 0)
        return std::nullopt;

    // Update last_login
    int64_t now = now_unix();
    sqlite3_stmt* upd = nullptr;
    sqlite3_prepare_v2(db_, "UPDATE accounts SET last_login=? WHERE id=?", -1, &upd, nullptr);
    sqlite3_bind_int64(upd, 1, now);
    sqlite3_bind_int64(upd, 2, id);
    sqlite3_step(upd);
    sqlite3_finalize(upd);

    Account acc;
    acc.id         = id;
    acc.username   = username;
    acc.is_admin   = is_admin;
    acc.created_at = created;
    acc.last_login = now;
    return acc;
}

std::string Database::generate_password(size_t length) {
    static const char kAlphabet[] =
        "ABCDEFGHJKLMNPQRSTUVWXYZabcdefghjkmnpqrstuvwxyz23456789!@#$%^&*";
    constexpr size_t kAlphaLen = sizeof(kAlphabet) - 1;
    std::string pw;
    pw.reserve(length);
    for (size_t i = 0; i < length; ++i) {
        uint8_t rnd[1];
        randombytes_buf(rnd, 1);
        pw += kAlphabet[rnd[0] % kAlphaLen];
    }
    return pw;
}

bool Database::exec(const std::string& sql, std::string& error) {
    char* errmsg = nullptr;
    int rc = sqlite3_exec(db_, sql.c_str(), nullptr, nullptr, &errmsg);
    if (rc != SQLITE_OK) {
        error = errmsg ? errmsg : "unknown error";
        if (errmsg) sqlite3_free(errmsg);
        return false;
    }
    return true;
}

int64_t Database::now_unix() const {
    using namespace std::chrono;
    return duration_cast<seconds>(system_clock::now().time_since_epoch()).count();
}

}  // namespace voicecat::server

#endif  // VOICECAT_HAS_NET