#include "sqliteInt.h"
#include "unity.h"
#include <string.h>
#include <stdlib.h>

/* Unity setUp/tearDown */
void setUp(void) {
  /* No global setup required */
}
void tearDown(void) {
  /* No global teardown required */
}

/* Helper: create a SrcList with one item for table zTab in database zDb (or NULL for main) */
static SrcList *makeSrcListOne(sqlite3 *db, const char *zDb, const char *zTab){
  /* SrcList has a flexible array a[1], so sizeof(SrcList) is sufficient for one element */
  SrcList *p = (SrcList*)sqlite3DbMallocZero(db, sizeof(SrcList));
  TEST_ASSERT_NOT_NULL_MESSAGE(p, "sqlite3DbMallocZero failed creating SrcList");
  p->nAlloc = 1;
  p->nSrc = 1;
  p->a[0].zName = sqlite3DbStrDup(db, zTab);
  TEST_ASSERT_NOT_NULL_MESSAGE(p->a[0].zName, "sqlite3DbStrDup failed for table name");
  if( zDb ){
    p->a[0].zDatabase = sqlite3DbStrDup(db, zDb);
    TEST_ASSERT_NOT_NULL_MESSAGE(p->a[0].zDatabase, "sqlite3DbStrDup failed for database name");
  }
  return p;
}

/* Helper: make a Token from a C string literal */
static Token makeToken(const char *z){
  Token t;
  t.z = z;
  t.n = (int)strlen(z);
  return t;
}

/* Helper: initialize a Parse object for a given db */
static void initParse(Parse *pParse, sqlite3 *db){
  memset(pParse, 0, sizeof(*pParse));
  pParse->db = db;
}

/* Helper: exec SQL and assert SQLITE_OK */
static void execSqlOk(sqlite3 *db, const char *zSql){
  int rc = sqlite3_exec(db, zSql, 0, 0, 0);
  if( rc!=SQLITE_OK ){
    const char *err = sqlite3_errmsg(db);
    char msg[512];
    sqlite3_snprintf(sizeof(msg), msg, "SQL exec failed (%d): %s; SQL: %s", rc, err ? err : "(null)", zSql);
    TEST_FAIL_MESSAGE(msg);
  }
}

/* Test: Nonexistent table should cause early return: no VDBE and an error recorded */
void test_sqlite3AlterDropConstraint_nonexistent_table(void){
  sqlite3 *db = 0;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));
  Parse p;
  initParse(&p, db);

  SrcList *pSrc = makeSrcListOne(db, NULL, "nosuchtable");
  Token cons = makeToken("c1");

  sqlite3AlterDropConstraint(&p, pSrc, &cons, 0);

  TEST_ASSERT_NULL_MESSAGE(p.pVdbe, "VDBE should not be created for nonexistent table");
  TEST_ASSERT_TRUE_MESSAGE(p.nErr>0, "An error should be recorded for nonexistent table");

  sqlite3SrcListDelete(db, pSrc);
  if( p.pVdbe ) sqlite3VdbeDelete(p.pVdbe);
  sqlite3_close(db);
}

/* Test: Existing table, drop NOT NULL from existing column -> code generated (VDBE created) */
void test_sqlite3AlterDropConstraint_drop_not_null_on_existing_col_generates_code(void){
  sqlite3 *db = 0;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));
  execSqlOk(db, "CREATE TABLE t1(a INTEGER NOT NULL, b TEXT);");

  Parse p;
  initParse(&p, db);

  SrcList *pSrc = makeSrcListOne(db, NULL, "t1");
  Token col = makeToken("a");

  sqlite3AlterDropConstraint(&p, pSrc, 0, &col);

  TEST_ASSERT_NOT_NULL_MESSAGE(p.pVdbe, "VDBE should be created for valid DROP NOT NULL operation");
  /* We do not execute the VDBE here; we only ensure code generation occurred. */

  sqlite3SrcListDelete(db, pSrc);
  if( p.pVdbe ) sqlite3VdbeDelete(p.pVdbe);
  sqlite3_close(db);
}

/* Test: Existing table, drop NOT NULL from nonexistent column -> error, no VDBE */
void test_sqlite3AlterDropConstraint_nonexistent_column_reports_error(void){
  sqlite3 *db = 0;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));
  execSqlOk(db, "CREATE TABLE t2(a INTEGER NOT NULL, b TEXT);");

  Parse p;
  initParse(&p, db);

  SrcList *pSrc = makeSrcListOne(db, NULL, "t2");
  Token col = makeToken("no_such_col");

  sqlite3AlterDropConstraint(&p, pSrc, 0, &col);

  TEST_ASSERT_NULL_MESSAGE(p.pVdbe, "VDBE should not be created when column does not exist");
  TEST_ASSERT_TRUE_MESSAGE(p.nErr>0, "An error should be recorded for nonexistent column");

  sqlite3SrcListDelete(db, pSrc);
  if( p.pVdbe ) sqlite3VdbeDelete(p.pVdbe);
  sqlite3_close(db);
}

/* Test: Existing table with named constraint, drop named constraint -> code generated */
void test_sqlite3AlterDropConstraint_drop_named_constraint_generates_code(void){
  sqlite3 *db = 0;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));
  /* Create a table with a named CHECK constraint */
  execSqlOk(db, "CREATE TABLE t3(x INT, y INT, CONSTRAINT c1 CHECK(x>0));");

  Parse p;
  initParse(&p, db);

  SrcList *pSrc = makeSrcListOne(db, NULL, "t3");
  Token cons = makeToken("c1");

  sqlite3AlterDropConstraint(&p, pSrc, &cons, 0);

  TEST_ASSERT_NOT_NULL_MESSAGE(p.pVdbe, "VDBE should be created for valid DROP CONSTRAINT operation");

  sqlite3SrcListDelete(db, pSrc);
  if( p.pVdbe ) sqlite3VdbeDelete(p.pVdbe);
  sqlite3_close(db);
}

int main(void){
  UNITY_BEGIN();
  RUN_TEST(test_sqlite3AlterDropConstraint_nonexistent_table);
  RUN_TEST(test_sqlite3AlterDropConstraint_drop_not_null_on_existing_col_generates_code);
  RUN_TEST(test_sqlite3AlterDropConstraint_nonexistent_column_reports_error);
  RUN_TEST(test_sqlite3AlterDropConstraint_drop_named_constraint_generates_code);
  return UNITY_END();
}