#include "sqliteInt.h"
#include "unity.h"

#include <stdlib.h>
#include <string.h>

/* The wrapper for the static function is provided by the module build. */
extern void test_dropColumnFunc(sqlite3_context *context, int NotUsed, sqlite3_value **argv);

static sqlite3 *gDb = NULL;

/* UDF trampoline that forwards directly to the function-under-test. */
static void udf_call_drop_column(sqlite3_context *ctx, int argc, sqlite3_value **argv){
  /* Expect exactly 3 arguments as specified by dropColumnFunc. */
  if( argc!=3 ){
    sqlite3_result_error_code(ctx, SQLITE_MISUSE);
    return;
  }
  test_dropColumnFunc(ctx, 0, argv);
}

/* Helper: Execute SELECT call_drop_column(?, ?, ?) and capture result text or error. */
static int run_drop_and_capture(
  int iSchema,                  /* argv[0] */
  const char *zCreate,          /* argv[1] - may be NULL */
  int iCol,                     /* argv[2] */
  char **pzResult,              /* OUT: sqlite3_malloc'ed copy (via sqlite3_mprintf) of result text if SQLITE_ROW */
  int *pDbErr                   /* OUT: sqlite3_errcode(db) if not SQLITE_ROW, else SQLITE_OK */
){
  sqlite3_stmt *pStmt = NULL;
  int rcPrep = sqlite3_prepare_v2(gDb, "SELECT call_drop_column(?, ?, ?)", -1, &pStmt, 0);
  if( rcPrep!=SQLITE_OK ){
    if( pDbErr ) *pDbErr = rcPrep;
    return rcPrep;
  }
  sqlite3_bind_int(pStmt, 1, iSchema);
  if( zCreate ){
    sqlite3_bind_text(pStmt, 2, zCreate, -1, SQLITE_TRANSIENT);
  }else{
    sqlite3_bind_null(pStmt, 2);
  }
  sqlite3_bind_int(pStmt, 3, iCol);

  int rcStep = sqlite3_step(pStmt);
  if( rcStep==SQLITE_ROW ){
    const unsigned char *z = sqlite3_column_text(pStmt, 0);
    if( z && pzResult ){
      *pzResult = sqlite3_mprintf("%s", z);
    }
    if( pDbErr ) *pDbErr = SQLITE_OK;
  }else{
    if( pDbErr ) *pDbErr = sqlite3_errcode(gDb);
  }

  sqlite3_finalize(pStmt);
  return rcStep;
}

void setUp(void) {
  int rc = sqlite3_open(":memory:", &gDb);
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, rc);
  sqlite3_extended_result_codes(gDb, 1);
  rc = sqlite3_create_function(gDb, "call_drop_column", 3, SQLITE_UTF8, NULL,
                               udf_call_drop_column, NULL, NULL);
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, rc);
}

void tearDown(void) {
  if( gDb ){
    sqlite3_close(gDb);
    gDb = NULL;
  }
}

/* Simple: drop first column */
void test_dropColumnFunc_drop_first_simple(void){
  char *zOut = NULL; int err = SQLITE_OK;
  int rc = run_drop_and_capture(0, "CREATE TABLE t(a,b,c)", 0, &zOut, &err);
  TEST_ASSERT_EQUAL_INT(SQLITE_ROW, rc);
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, err);
  TEST_ASSERT_NOT_NULL(zOut);
  TEST_ASSERT_EQUAL_STRING("CREATE TABLE t(b,c)", zOut);
  sqlite3_free(zOut);
}

/* Simple: drop middle column */
void test_dropColumnFunc_drop_middle_simple(void){
  char *zOut = NULL; int err = SQLITE_OK;
  int rc = run_drop_and_capture(0, "CREATE TABLE t(a,b,c)", 1, &zOut, &err);
  TEST_ASSERT_EQUAL_INT(SQLITE_ROW, rc);
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, err);
  TEST_ASSERT_NOT_NULL(zOut);
  TEST_ASSERT_EQUAL_STRING("CREATE TABLE t(a,c)", zOut);
  sqlite3_free(zOut);
}

/* Simple: drop last column */
void test_dropColumnFunc_drop_last_simple(void){
  char *zOut = NULL; int err = SQLITE_OK;
  int rc = run_drop_and_capture(0, "CREATE TABLE t(a,b,c)", 2, &zOut, &err);
  TEST_ASSERT_EQUAL_INT(SQLITE_ROW, rc);
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, err);
  TEST_ASSERT_NOT_NULL(zOut);
  TEST_ASSERT_EQUAL_STRING("CREATE TABLE t(a,b)", zOut);
  sqlite3_free(zOut);
}

/* Drop last column when previous column has nested parentheses and commas in constraints */
void test_dropColumnFunc_drop_last_with_nested_constraints(void){
  const char *zCreate =
    "CREATE TABLE t(a, b TEXT CHECK(b IN (1,2,3) AND (b IS NOT NULL)), c)";
  char *zOut = NULL; int err = SQLITE_OK;
  int rc = run_drop_and_capture(0, zCreate, 2, &zOut, &err);
  TEST_ASSERT_EQUAL_INT(SQLITE_ROW, rc);
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, err);
  TEST_ASSERT_NOT_NULL(zOut);
  TEST_ASSERT_EQUAL_STRING(
    "CREATE TABLE t(a, b TEXT CHECK(b IN (1,2,3) AND (b IS NOT NULL)))", zOut);
  sqlite3_free(zOut);
}

/* Error: invalid column index (>= nCol) */
void test_dropColumnFunc_invalid_index_error(void){
  int err = SQLITE_OK;
  int rc = run_drop_and_capture(0, "CREATE TABLE t(a,b)", 5, NULL, &err);
  TEST_ASSERT_EQUAL_INT(SQLITE_ERROR, rc);
  TEST_ASSERT_EQUAL_INT(SQLITE_CORRUPT, err);
}

/* Error: single-column table cannot drop (nCol==1) */
void test_dropColumnFunc_single_column_error(void){
  int err = SQLITE_OK;
  int rc = run_drop_and_capture(0, "CREATE TABLE t(a)", 0, NULL, &err);
  TEST_ASSERT_EQUAL_INT(SQLITE_ERROR, rc);
  TEST_ASSERT_EQUAL_INT(SQLITE_CORRUPT, err);
}

/* Error: SQL not starting with CREATE should produce corruption error */
void test_dropColumnFunc_invalid_sql_error(void){
  int err = SQLITE_OK;
  int rc = run_drop_and_capture(0, "DROP TABLE t", 0, NULL, &err);
  TEST_ASSERT_EQUAL_INT(SQLITE_ERROR, rc);
  TEST_ASSERT_EQUAL_INT(SQLITE_CORRUPT, err);
}

/* Temp schema path (iSchema==1) */
void test_dropColumnFunc_temp_schema(void){
  char *zOut = NULL; int err = SQLITE_OK;
  int rc = run_drop_and_capture(1, "CREATE TABLE t(a,b)", 1, &zOut, &err);
  TEST_ASSERT_EQUAL_INT(SQLITE_ROW, rc);
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, err);
  TEST_ASSERT_NOT_NULL(zOut);
  TEST_ASSERT_EQUAL_STRING("CREATE TABLE t(a)", zOut);
  sqlite3_free(zOut);
}

/* Quoted identifiers and spacing preserved */
void test_dropColumnFunc_preserves_quotes_and_spacing(void){
  const char *zCreate =
    "CREATE TABLE \"My T\"( \"a1\" INTEGER PRIMARY KEY, \"b-2\" TEXT, c )";
  char *zOut = NULL; int err = SQLITE_OK;
  int rc = run_drop_and_capture(0, zCreate, 1, &zOut, &err);
  TEST_ASSERT_EQUAL_INT(SQLITE_ROW, rc);
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, err);
  TEST_ASSERT_NOT_NULL(zOut);
  TEST_ASSERT_EQUAL_STRING(
    "CREATE TABLE \"My T\"( \"a1\" INTEGER PRIMARY KEY, c )", zOut);
  sqlite3_free(zOut);
}

/* NULL SQL argument -> treated as SQLITE_NOMEM by renameParseSql */
void test_dropColumnFunc_null_sql_error(void){
  int err = SQLITE_OK;
  int rc = run_drop_and_capture(0, NULL, 0, NULL, &err);
  TEST_ASSERT_EQUAL_INT(SQLITE_ERROR, rc);
  TEST_ASSERT_EQUAL_INT(SQLITE_NOMEM, err);
}

int main(void) {
  UNITY_BEGIN();
  RUN_TEST(test_dropColumnFunc_drop_first_simple);
  RUN_TEST(test_dropColumnFunc_drop_middle_simple);
  RUN_TEST(test_dropColumnFunc_drop_last_simple);
  RUN_TEST(test_dropColumnFunc_drop_last_with_nested_constraints);
  RUN_TEST(test_dropColumnFunc_invalid_index_error);
  RUN_TEST(test_dropColumnFunc_single_column_error);
  RUN_TEST(test_dropColumnFunc_invalid_sql_error);
  RUN_TEST(test_dropColumnFunc_temp_schema);
  RUN_TEST(test_dropColumnFunc_preserves_quotes_and_spacing);
  RUN_TEST(test_dropColumnFunc_null_sql_error);
  return UNITY_END();
}