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

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

/* Helpers */
static int exec_sql(sqlite3 *db, const char *sql, char **pzErr){
  return sqlite3_exec(db, sql, 0, 0, pzErr);
}

static void assert_exec_ok(sqlite3 *db, const char *sql){
  char *zErr = NULL;
  int rc = exec_sql(db, sql, &zErr);
  if( zErr ){
    /* Ensure any error message is freed even if rc==SQLITE_OK (unlikely) */
    sqlite3_free(zErr);
    zErr = NULL;
  }
  TEST_ASSERT_EQUAL_INT_MESSAGE(SQLITE_OK, rc, sql);
}

static int exec_expect_error_contains(sqlite3 *db, const char *sql, const char *needle, int *pRcOut){
  char *zErr = NULL;
  int rc = exec_sql(db, sql, &zErr);
  if( pRcOut ) *pRcOut = rc;
  int ok = (rc!=SQLITE_OK) && (zErr!=NULL) && (strstr(zErr, needle)!=0);
  if( zErr ) sqlite3_free(zErr);
  return ok;
}

static char *get_table_sql(sqlite3 *db, const char *zName){
  sqlite3_stmt *pStmt = NULL;
  const char *zSql = "SELECT sql FROM sqlite_schema WHERE name=?1";
  if( sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0)!=SQLITE_OK ){
    return NULL;
  }
  sqlite3_bind_text(pStmt, 1, zName, -1, SQLITE_STATIC);
  char *zOut = NULL;
  if( sqlite3_step(pStmt)==SQLITE_ROW ){
    const unsigned char *z = sqlite3_column_text(pStmt, 0);
    if( z ){
      zOut = sqlite3_mprintf("%s", z);
    }
  }
  sqlite3_finalize(pStmt);
  return zOut;
}

/* Unity fixtures */
void setUp(void) {
  /* empty */
}
void tearDown(void) {
  /* empty */
}

/* Test: Successful ALTER adds named constraint and enforces it for new rows */
void test_sqlite3AlterAddConstraint_add_named_and_enforce(void){
  sqlite3 *db = NULL;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));

  assert_exec_ok(db, "CREATE TABLE t1(x)");
  assert_exec_ok(db, "INSERT INTO t1 VALUES(1)");

  /* Add a named CHECK constraint */
  assert_exec_ok(db, "ALTER TABLE t1 ADD CONSTRAINT ck_pos CHECK(x>0)");

  /* Inserting a violating row should now fail */
  int rc = SQLITE_OK;
  TEST_ASSERT_TRUE_MESSAGE(
    exec_expect_error_contains(db, "INSERT INTO t1 VALUES(0)", "CHECK constraint failed", &rc),
    "Expected CHECK constraint failure on INSERT after ALTER"
  );
  TEST_ASSERT_EQUAL_INT_MESSAGE(SQLITE_CONSTRAINT, rc, "Expected SQLITE_CONSTRAINT");

  /* Valid insert still succeeds */
  assert_exec_ok(db, "INSERT INTO t1 VALUES(2)");

  /* Adding another constraint with the same name should fail */
  TEST_ASSERT_TRUE_MESSAGE(
    exec_expect_error_contains(db,
      "ALTER TABLE t1 ADD CONSTRAINT ck_pos CHECK(x<10)",
      "already exists",
      NULL
    ),
    "Expected duplicate constraint name error"
  );

  sqlite3_close(db);
}

/* Test: ALTER fails if existing rows violate the new CHECK expression */
void test_sqlite3AlterAddConstraint_violation_on_alter(void){
  sqlite3 *db = NULL;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));

  assert_exec_ok(db, "CREATE TABLE t2(x)");
  assert_exec_ok(db, "INSERT INTO t2 VALUES(-1)");

  /* This should fail because existing row violates x>0 */
  int rc = SQLITE_OK;
  TEST_ASSERT_TRUE_MESSAGE(
    exec_expect_error_contains(db,
      "ALTER TABLE t2 ADD CHECK(x>0)",
      "constraint failed",
      &rc
    ),
    "Expected 'constraint failed' during ALTER due to existing data"
  );
  TEST_ASSERT_EQUAL_INT_MESSAGE(SQLITE_CONSTRAINT, rc, "Expected SQLITE_CONSTRAINT");

  /* Schema should not be modified */
  char *zSchema = get_table_sql(db, "t2");
  TEST_ASSERT_NOT_NULL(zSchema);
  TEST_ASSERT_TRUE(strstr(zSchema, "CHECK")==NULL);
  sqlite3_free(zSchema);

  sqlite3_close(db);
}

/* Test: Trailing '--' is trimmed but trailing '/* ... *\/' comment is preserved */
void test_sqlite3AlterAddConstraint_trim_line_comment_preserve_c_comment(void){
  sqlite3 *db = NULL;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));

  assert_exec_ok(db, "CREATE TABLE t3(x)");
  assert_exec_ok(db, "INSERT INTO t3 VALUES(1)");

  /* Trailing C-style comment should be preserved; trailing -- comment removed */
  assert_exec_ok(db, "ALTER TABLE t3 ADD CHECK (x>0) /*C-keep*/ -- line-drop");

  char *zSchema = get_table_sql(db, "t3");
  TEST_ASSERT_NOT_NULL(zSchema);

  /* Ensure C-style comment present, '--' tail absent */
  TEST_ASSERT_NOT_NULL_MESSAGE(strstr(zSchema, "/*C-keep*/"), "Expected C-style comment preserved in schema SQL");
  TEST_ASSERT_NULL_MESSAGE(strstr(zSchema, "-- line-drop"), "Expected '--' trailing comment removed from schema SQL");

  sqlite3_free(zSchema);
  sqlite3_close(db);
}

/* Direct call smoke test: invoke sqlite3AlterAddConstraint with constructed Parse/SrcList/Tokens */
void test_sqlite3AlterAddConstraint_direct_call_smoke(void){
  sqlite3 *db = NULL;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));
  assert_exec_ok(db, "CREATE TABLE t4(a)");

  /* Prepare Parse with a Vdbe */
  Parse p;
  memset(&p, 0, sizeof(p));
  p.db = db;
  /* Ensure there is a VDBE to receive generated bytecode */
  sqlite3GetVdbe(&p);
  TEST_ASSERT_NOT_NULL(p.pVdbe);

  /* Build a SrcList referring to table t4 */
  Token tTbl = { "t4", 2 };
  SrcList *pSrc = sqlite3SrcListAppend(db, 0, &tTbl, 0);
  TEST_ASSERT_NOT_NULL(pSrc);
  TEST_ASSERT_EQUAL_INT(1, pSrc->nSrc);

  /* Construct constraint text and tokens */
  const char *zCons = "CONSTRAINT ckx CHECK(a>0) /*preserve*/ -- trim";
  Token firstTok;
  firstTok.z = zCons;
  firstTok.n = (int)strlen(zCons);
  Token nameTok = { "ckx", 3 };
  const char *zExpr = "a>0";
  int nExpr = 3;

  /* Set sLastToken to mark the end of the constraint text buffer */
  p.sLastToken.z = zCons + strlen(zCons);
  p.sLastToken.n = 0;

  /* Invoke the target function directly */
  sqlite3AlterAddConstraint(&p, pSrc, &firstTok, &nameTok, zExpr, nExpr);

  /* Basic sanity: no parse errors recorded and VDBE remains allocated */
  TEST_ASSERT_NOT_NULL(p.pVdbe);
  TEST_ASSERT_EQUAL_INT(0, p.nErr);

  /* Cleanup */
  sqlite3SrcListDelete(db, pSrc);
  sqlite3VdbeDelete(p.pVdbe);
  sqlite3_close(db);
}

int main(void) {
  UNITY_BEGIN();
  RUN_TEST(test_sqlite3AlterAddConstraint_add_named_and_enforce);
  RUN_TEST(test_sqlite3AlterAddConstraint_violation_on_alter);
  RUN_TEST(test_sqlite3AlterAddConstraint_trim_line_comment_preserve_c_comment);
  RUN_TEST(test_sqlite3AlterAddConstraint_direct_call_smoke);
  return UNITY_END();
}