#![allow(clippy::missing_safety_doc)]
#![allow(non_camel_case_types)]

use log::trace;
use std::cell::RefCell;
use std::ffi;

use std::rc::Rc;
use std::sync::Arc;

macro_rules! stub {
    () => {
        todo!("{} is not implemented", stringify!($fn));
    };
}

pub const SQLITE_OK: ffi::c_int = 0;
pub const SQLITE_ERROR: ffi::c_int = 1;
pub const SQLITE_ABORT: ffi::c_int = 4;
pub const SQLITE_BUSY: ffi::c_int = 5;
pub const SQLITE_NOMEM: ffi::c_int = 7;
pub const SQLITE_NOTFOUND: ffi::c_int = 14;
pub const SQLITE_MISUSE: ffi::c_int = 21;
pub const SQLITE_ROW: ffi::c_int = 100;
pub const SQLITE_DONE: ffi::c_int = 101;
pub const SQLITE_ABORT_ROLLBACK: ffi::c_int = SQLITE_ABORT | (2 << 8);
pub const SQLITE_STATE_OPEN: u8 = 0x76;
pub const SQLITE_STATE_SICK: u8 = 0xba;
pub const SQLITE_STATE_BUSY: u8 = 0x6d;

pub mod util;

use util::sqlite3_safety_check_sick_or_ok;

pub struct sqlite3 {
    pub(crate) _db: Arc<limbo_core::Database>,
    pub(crate) conn: Rc<limbo_core::Connection>,
    pub(crate) err_code: ffi::c_int,
    pub(crate) err_mask: ffi::c_int,
    pub(crate) malloc_failed: bool,
    pub(crate) e_open_state: u8,
    pub(crate) p_err: *mut std::ffi::c_void,
}

impl sqlite3 {
    pub fn new(db: Arc<limbo_core::Database>, conn: Rc<limbo_core::Connection>) -> Self {
        Self {
            _db: db,
            conn,
            err_code: SQLITE_OK,
            err_mask: 0xFFFFFFFFu32 as i32,
            malloc_failed: false,
            e_open_state: SQLITE_STATE_OPEN,
            p_err: std::ptr::null_mut(),
        }
    }
}

pub struct sqlite3_stmt<'a> {
    pub(crate) stmt: limbo_core::Statement,
    pub(crate) row: RefCell<Option<limbo_core::Row<'a>>>,
}

impl<'a> sqlite3_stmt<'a> {
    pub fn new(stmt: limbo_core::Statement) -> Self {
        let row = RefCell::new(None);
        Self { stmt, row }
    }
}

static INIT_DONE: std::sync::Once = std::sync::Once::new();

#[no_mangle]
pub unsafe extern "C" fn sqlite3_initialize() -> ffi::c_int {
    INIT_DONE.call_once(|| {
        env_logger::init();
    });
    SQLITE_OK
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_shutdown() -> ffi::c_int {
    SQLITE_OK
}

#[no_mangle]
#[allow(clippy::arc_with_non_send_sync)]
pub unsafe extern "C" fn sqlite3_open(
    filename: *const ffi::c_char,
    db_out: *mut *mut sqlite3,
) -> ffi::c_int {
    trace!("sqlite3_open");
    let rc = sqlite3_initialize();
    if rc != SQLITE_OK {
        return rc;
    }
    if filename.is_null() {
        return SQLITE_MISUSE;
    }
    if db_out.is_null() {
        return SQLITE_MISUSE;
    }
    let filename = ffi::CStr::from_ptr(filename);
    let filename = match filename.to_str() {
        Ok(s) => s,
        Err(_) => return SQLITE_MISUSE,
    };
    let io = match limbo_core::PlatformIO::new() {
        Ok(io) => Arc::new(io),
        Err(_) => return SQLITE_MISUSE,
    };
    match limbo_core::Database::open_file(io, filename) {
        Ok(db) => {
            let conn = db.connect();
            *db_out = Box::leak(Box::new(sqlite3::new(db, conn)));
            SQLITE_OK
        }
        Err(_e) => SQLITE_NOTFOUND,
    }
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_open_v2(
    filename: *const ffi::c_char,
    db_out: *mut *mut sqlite3,
    _flags: ffi::c_int,
    _z_vfs: *const ffi::c_char,
) -> ffi::c_int {
    trace!("sqlite3_open_v2");
    sqlite3_open(filename, db_out)
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_close(db: *mut sqlite3) -> ffi::c_int {
    trace!("sqlite3_close");
    if db.is_null() {
        return SQLITE_OK;
    }
    let _ = Box::from_raw(db);
    SQLITE_OK
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_close_v2(db: *mut sqlite3) -> ffi::c_int {
    trace!("sqlite3_close_v2");
    sqlite3_close(db)
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_trace_v2(
    _db: *mut sqlite3,
    _mask: ffi::c_uint,
    _callback: Option<
        unsafe extern "C" fn(
            ffi::c_uint,
            *mut std::ffi::c_void,
            *mut std::ffi::c_void,
            *mut std::ffi::c_void,
        ),
    >,
    _context: *mut std::ffi::c_void,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_progress_handler(
    _db: *mut sqlite3,
    _n: ffi::c_int,
    _callback: Option<unsafe extern "C" fn() -> ffi::c_int>,
    _context: *mut std::ffi::c_void,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_busy_timeout(_db: *mut sqlite3, _ms: ffi::c_int) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_set_authorizer(
    _db: *mut sqlite3,
    _callback: Option<unsafe extern "C" fn() -> ffi::c_int>,
    _context: *mut std::ffi::c_void,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_context_db_handle(
    _context: *mut std::ffi::c_void,
) -> *mut std::ffi::c_void {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_prepare_v2(
    db: *mut sqlite3,
    sql: *const ffi::c_char,
    _len: ffi::c_int,
    out_stmt: *mut *mut sqlite3_stmt,
    _tail: *mut *const ffi::c_char,
) -> ffi::c_int {
    if db.is_null() || sql.is_null() || out_stmt.is_null() {
        return SQLITE_MISUSE;
    }
    let db: &mut sqlite3 = &mut *db;
    let sql = ffi::CStr::from_ptr(sql);
    let sql = match sql.to_str() {
        Ok(s) => s,
        Err(_) => return SQLITE_MISUSE,
    };
    let stmt = match db.conn.prepare(sql) {
        Ok(stmt) => stmt,
        Err(_) => return SQLITE_ERROR,
    };
    *out_stmt = Box::leak(Box::new(sqlite3_stmt::new(stmt)));
    SQLITE_OK
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_finalize(stmt: *mut sqlite3_stmt) -> ffi::c_int {
    if stmt.is_null() {
        return SQLITE_MISUSE;
    }
    let _ = Box::from_raw(stmt);
    SQLITE_OK
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_step(stmt: *mut sqlite3_stmt) -> std::ffi::c_int {
    let stmt = &mut *stmt;
    if let Ok(result) = stmt.stmt.step() {
        match result {
            limbo_core::RowResult::IO => SQLITE_BUSY,
            limbo_core::RowResult::Done => SQLITE_DONE,
            limbo_core::RowResult::Row(row) => {
                stmt.row.replace(Some(row));
                SQLITE_ROW
            }
        }
    } else {
        SQLITE_ERROR
    }
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_exec(
    db: *mut sqlite3,
    sql: *const ffi::c_char,
    _callback: Option<unsafe extern "C" fn() -> ffi::c_int>,
    _context: *mut std::ffi::c_void,
    _err: *mut *mut std::ffi::c_char,
) -> ffi::c_int {
    if db.is_null() || sql.is_null() {
        return SQLITE_MISUSE;
    }
    let db: &mut sqlite3 = &mut *db;
    let sql = ffi::CStr::from_ptr(sql);
    let sql = match sql.to_str() {
        Ok(s) => s,
        Err(_) => return SQLITE_MISUSE,
    };
    match db.conn.execute(sql) {
        Ok(_) => SQLITE_OK,
        Err(_) => SQLITE_ERROR,
    }
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_reset(stmt: *mut sqlite3_stmt) -> ffi::c_int {
    let stmt = &mut *stmt;
    stmt.row.replace(None);
    SQLITE_OK
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_changes(_db: *mut sqlite3) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_stmt_readonly(_stmt: *mut sqlite3_stmt) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_stmt_busy(_stmt: *mut sqlite3_stmt) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_serialize(
    _db: *mut sqlite3,
    _schema: *const std::ffi::c_char,
    _out: *mut *mut std::ffi::c_void,
    _out_bytes: *mut ffi::c_int,
    _flags: ffi::c_uint,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_deserialize(
    _db: *mut sqlite3,
    _schema: *const std::ffi::c_char,
    _in_: *const std::ffi::c_void,
    _in_bytes: ffi::c_int,
    _flags: ffi::c_uint,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_get_autocommit(_db: *mut sqlite3) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_total_changes(_db: *mut sqlite3) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_last_insert_rowid(_db: *mut sqlite3) -> i64 {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_interrupt(_db: *mut sqlite3) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_db_config(_db: *mut sqlite3, _op: ffi::c_int) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_db_handle(_stmt: *mut sqlite3_stmt) -> *mut sqlite3 {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_sleep(_ms: ffi::c_int) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_limit(
    _db: *mut sqlite3,
    _id: ffi::c_int,
    _new_value: ffi::c_int,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_malloc64(_n: ffi::c_int) -> *mut std::ffi::c_void {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_free(_ptr: *mut std::ffi::c_void) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_errcode(_db: *mut sqlite3) -> ffi::c_int {
    if !_db.is_null() && !sqlite3_safety_check_sick_or_ok(&*_db) {
        return SQLITE_MISUSE;
    }

    if _db.is_null() || (*_db).malloc_failed {
        return SQLITE_NOMEM;
    }

    (*_db).err_code & (*_db).err_mask
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_errstr(_err: ffi::c_int) -> *const std::ffi::c_char {
    sqlite3_errstr_impl(_err)
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_user_data(
    _context: *mut std::ffi::c_void,
) -> *mut std::ffi::c_void {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_backup_init(
    _dest_db: *mut sqlite3,
    _dest_name: *const std::ffi::c_char,
    _source_db: *mut sqlite3,
    _source_name: *const std::ffi::c_char,
) -> *mut std::ffi::c_void {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_backup_step(
    _backup: *mut std::ffi::c_void,
    _n_pages: ffi::c_int,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_backup_remaining(_backup: *mut std::ffi::c_void) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_backup_pagecount(_backup: *mut std::ffi::c_void) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_backup_finish(_backup: *mut std::ffi::c_void) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_expanded_sql(_stmt: *mut sqlite3_stmt) -> *mut std::ffi::c_char {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_data_count(stmt: *mut sqlite3_stmt) -> ffi::c_int {
    let stmt = &*stmt;
    let row = stmt.row.borrow();
    let row = match row.as_ref() {
        Some(row) => row,
        None => return 0,
    };
    row.values.len() as ffi::c_int
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_bind_parameter_count(_stmt: *mut sqlite3_stmt) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_bind_parameter_name(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
) -> *const std::ffi::c_char {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_bind_null(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_bind_int64(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
    _val: i64,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_bind_double(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
    _val: f64,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_bind_text(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
    _text: *const std::ffi::c_char,
    _len: ffi::c_int,
    _destroy: *mut std::ffi::c_void,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_bind_blob(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
    _blob: *const std::ffi::c_void,
    _len: ffi::c_int,
    _destroy: *mut std::ffi::c_void,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_column_type(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_column_count(_stmt: *mut sqlite3_stmt) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_column_decltype(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
) -> *const std::ffi::c_char {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_column_name(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
) -> *const std::ffi::c_char {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_column_int64(_stmt: *mut sqlite3_stmt, _idx: ffi::c_int) -> i64 {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_column_double(_stmt: *mut sqlite3_stmt, _idx: ffi::c_int) -> f64 {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_column_blob(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
) -> *const std::ffi::c_void {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_column_bytes(
    _stmt: *mut sqlite3_stmt,
    _idx: ffi::c_int,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_value_type(value: *mut std::ffi::c_void) -> ffi::c_int {
    let value = value as *mut limbo_core::Value;
    let value = &*value;
    match value {
        limbo_core::Value::Null => 0,
        limbo_core::Value::Integer(_) => 1,
        limbo_core::Value::Float(_) => 2,
        limbo_core::Value::Text(_) => 3,
        limbo_core::Value::Blob(_) => 4,
    }
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_value_int64(value: *mut std::ffi::c_void) -> i64 {
    let value = value as *mut limbo_core::Value;
    let value = &*value;
    match value {
        limbo_core::Value::Integer(i) => *i,
        _ => 0,
    }
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_value_double(value: *mut std::ffi::c_void) -> f64 {
    let value = value as *mut limbo_core::Value;
    let value = &*value;
    match value {
        limbo_core::Value::Float(f) => *f,
        _ => 0.0,
    }
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_value_text(
    value: *mut std::ffi::c_void,
) -> *const std::ffi::c_uchar {
    let value = value as *mut limbo_core::Value;
    let value = &*value;
    match value {
        limbo_core::Value::Text(text) => text.as_bytes().as_ptr(),
        _ => std::ptr::null(),
    }
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_value_blob(
    value: *mut std::ffi::c_void,
) -> *const std::ffi::c_void {
    let value = value as *mut limbo_core::Value;
    let value = &*value;
    match value {
        limbo_core::Value::Blob(blob) => blob.as_ptr() as *const std::ffi::c_void,
        _ => std::ptr::null(),
    }
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_value_bytes(value: *mut std::ffi::c_void) -> ffi::c_int {
    let value = value as *mut limbo_core::Value;
    let value = &*value;
    match value {
        limbo_core::Value::Blob(blob) => blob.len() as ffi::c_int,
        _ => 0,
    }
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_column_text(
    stmt: *mut sqlite3_stmt,
    idx: std::ffi::c_int,
) -> *const std::ffi::c_uchar {
    let stmt = &mut *stmt;
    let row = stmt.row.borrow();
    let row = match row.as_ref() {
        Some(row) => row,
        None => return std::ptr::null(),
    };
    match row.values.get(idx as usize) {
        Some(limbo_core::Value::Text(text)) => text.as_bytes().as_ptr(),
        _ => std::ptr::null(),
    }
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_result_null(_context: *mut std::ffi::c_void) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_result_int64(_context: *mut std::ffi::c_void, _val: i64) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_result_double(_context: *mut std::ffi::c_void, _val: f64) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_result_text(
    _context: *mut std::ffi::c_void,
    _text: *const std::ffi::c_char,
    _len: ffi::c_int,
    _destroy: *mut std::ffi::c_void,
) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_result_blob(
    _context: *mut std::ffi::c_void,
    _blob: *const std::ffi::c_void,
    _len: ffi::c_int,
    _destroy: *mut std::ffi::c_void,
) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_result_error_nomem(_context: *mut std::ffi::c_void) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_result_error_toobig(_context: *mut std::ffi::c_void) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_result_error(
    _context: *mut std::ffi::c_void,
    _err: *const std::ffi::c_char,
    _len: ffi::c_int,
) {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_aggregate_context(
    _context: *mut std::ffi::c_void,
    _n: ffi::c_int,
) -> *mut std::ffi::c_void {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_blob_open(
    _db: *mut sqlite3,
    _db_name: *const std::ffi::c_char,
    _table_name: *const std::ffi::c_char,
    _column_name: *const std::ffi::c_char,
    _rowid: i64,
    _flags: ffi::c_int,
    _blob_out: *mut *mut std::ffi::c_void,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_blob_read(
    _blob: *mut std::ffi::c_void,
    _data: *mut std::ffi::c_void,
    _n: ffi::c_int,
    _offset: ffi::c_int,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_blob_write(
    _blob: *mut std::ffi::c_void,
    _data: *const std::ffi::c_void,
    _n: ffi::c_int,
    _offset: ffi::c_int,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_blob_bytes(_blob: *mut std::ffi::c_void) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_blob_close(_blob: *mut std::ffi::c_void) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_stricmp(
    _a: *const std::ffi::c_char,
    _b: *const std::ffi::c_char,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_create_collation_v2(
    _db: *mut sqlite3,
    _name: *const std::ffi::c_char,
    _enc: ffi::c_int,
    _context: *mut std::ffi::c_void,
    _cmp: Option<unsafe extern "C" fn() -> ffi::c_int>,
    _destroy: Option<unsafe extern "C" fn()>,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_create_function_v2(
    _db: *mut sqlite3,
    _name: *const std::ffi::c_char,
    _n_args: ffi::c_int,
    _enc: ffi::c_int,
    _context: *mut std::ffi::c_void,
    _func: Option<unsafe extern "C" fn()>,
    _step: Option<unsafe extern "C" fn()>,
    _final_: Option<unsafe extern "C" fn()>,
    _destroy: Option<unsafe extern "C" fn()>,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_create_window_function(
    _db: *mut sqlite3,
    _name: *const std::ffi::c_char,
    _n_args: ffi::c_int,
    _enc: ffi::c_int,
    _context: *mut std::ffi::c_void,
    _x_step: Option<unsafe extern "C" fn()>,
    _x_final: Option<unsafe extern "C" fn()>,
    _x_value: Option<unsafe extern "C" fn()>,
    _x_inverse: Option<unsafe extern "C" fn()>,
    _destroy: Option<unsafe extern "C" fn()>,
) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_errmsg(_db: *mut sqlite3) -> *const std::ffi::c_char {
    if _db.is_null() {
        return sqlite3_errstr(SQLITE_NOMEM);
    }
    if !sqlite3_safety_check_sick_or_ok(&*_db) {
        return sqlite3_errstr(SQLITE_MISUSE);
    }
    if (*_db).malloc_failed {
        return sqlite3_errstr(SQLITE_NOMEM);
    }

    let err_msg = if (*_db).err_code != SQLITE_OK {
        if !(*_db).p_err.is_null() {
            (*_db).p_err as *const std::ffi::c_char
        } else {
            std::ptr::null()
        }
    } else {
        std::ptr::null()
    };

    if err_msg.is_null() {
        return sqlite3_errstr((*_db).err_code);
    }

    err_msg
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_extended_errcode(_db: *mut sqlite3) -> ffi::c_int {
    if !_db.is_null() && !sqlite3_safety_check_sick_or_ok(&*_db) {
        return SQLITE_MISUSE;
    }

    if _db.is_null() || (*_db).malloc_failed {
        return SQLITE_NOMEM;
    }

    (*_db).err_code & (*_db).err_mask
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_complete(_sql: *const std::ffi::c_char) -> ffi::c_int {
    stub!();
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_threadsafe() -> ffi::c_int {
    1
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_libversion() -> *const std::ffi::c_char {
    ffi::CStr::from_bytes_with_nul(b"3.42.0\0")
        .unwrap()
        .as_ptr()
}

#[no_mangle]
pub unsafe extern "C" fn sqlite3_libversion_number() -> ffi::c_int {
    3042000
}

fn sqlite3_errstr_impl(rc: i32) -> *const std::ffi::c_char {
    const ERROR_MESSAGES: [&str; 29] = [
        "not an error",                         // SQLITE_OK
        "SQL logic error",                      // SQLITE_ERROR
        "",                                     // SQLITE_INTERNAL
        "access permission denied",             // SQLITE_PERM
        "query aborted",                        // SQLITE_ABORT
        "database is locked",                   // SQLITE_BUSY
        "database table is locked",             // SQLITE_LOCKED
        "out of memory",                        // SQLITE_NOMEM
        "attempt to write a readonly database", // SQLITE_READONLY
        "interrupted",                          // SQLITE_INTERRUPT
        "disk I/O error",                       // SQLITE_IOERR
        "database disk image is malformed",     // SQLITE_CORRUPT
        "unknown operation",                    // SQLITE_NOTFOUND
        "database or disk is full",             // SQLITE_FULL
        "unable to open database file",         // SQLITE_CANTOPEN
        "locking protocol",                     // SQLITE_PROTOCOL
        "",                                     // SQLITE_EMPTY
        "database schema has changed",          // SQLITE_SCHEMA
        "string or blob too big",               // SQLITE_TOOBIG
        "constraint failed",                    // SQLITE_CONSTRAINT
        "datatype mismatch",                    // SQLITE_MISMATCH
        "bad parameter or other API misuse",    // SQLITE_MISUSE
        #[cfg(feature = "lfs")]
        "",      // SQLITE_NOLFS
        #[cfg(not(feature = "lfs"))]
        "large file support is disabled", // SQLITE_NOLFS
        "authorization denied",                 // SQLITE_AUTH
        "",                                     // SQLITE_FORMAT
        "column index out of range",            // SQLITE_RANGE
        "file is not a database",               // SQLITE_NOTADB
        "notification message",                 // SQLITE_NOTICE
        "warning message",                      // SQLITE_WARNING
    ];

    const UNKNOWN_ERROR: &str = "unknown error";
    const ABORT_ROLLBACK: &str = "abort due to ROLLBACK";
    const ANOTHER_ROW_AVAILABLE: &str = "another row available";
    const NO_MORE_ROWS_AVAILABLE: &str = "no more rows available";

    match rc {
        SQLITE_ABORT_ROLLBACK => ABORT_ROLLBACK.as_ptr() as *const std::ffi::c_char,
        SQLITE_ROW => ANOTHER_ROW_AVAILABLE.as_ptr() as *const std::ffi::c_char,
        SQLITE_DONE => NO_MORE_ROWS_AVAILABLE.as_ptr() as *const std::ffi::c_char,
        _ => {
            let rc = rc & 0xff;
            if rc >= 0
                && rc < ERROR_MESSAGES.len() as i32
                && !ERROR_MESSAGES[rc as usize].is_empty()
            {
                ERROR_MESSAGES[rc as usize].as_ptr() as *const std::ffi::c_char
            } else {
                UNKNOWN_ERROR.as_ptr() as *const std::ffi::c_char
            }
        }
    }
}