// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package sqlite provides access to the SQLite library, version 3.
package sqlite

/*
#cgo CFLAGS: -I.
#cgo CFLAGS: -DSQLITE_ENABLE_COLUMN_METADATA=1

#include <sqlite3.h>
#include <stdlib.h>

#if SQLITE_VERSION_NUMBER < 3007015
const char *sqlite3_errstr(int rc) {
	return "";
}
#endif
*/
import "C"

import (
	"errors"
	"fmt"
	"io"
	"os"
	"strconv"
	"time"
	"unsafe"
)

// OpenError is for detailed report on SQLite open failure.
type OpenError struct {
	Code         Errno // thread safe error code
	ExtendedCode int
	Msg          string
	Filename     string
}

func (e OpenError) Error() string {
	file := e.Filename
	if file == "" {
		file = "(temporary)"
	}
	s := fmt.Sprintf("%s: open: ", file)
	codeErr := e.Code.Error()
	if len(e.Msg) > 0 {
		s += e.Msg
		// error code and msg are often redundant but not always
		// (see sqlite3ErrorWithMsg usages in SQLite3 sources)
		if codeErr != e.Msg {
			s += fmt.Sprintf(" (%s)", codeErr)
		}
	} else {
		s += codeErr
	}
	return s
}

// ConnError is a wrapper for all SQLite connection related error.
type ConnError struct {
	c       *Conn
	code    Errno  // thread safe error code
	msg     string // it might be the case that a second error occurs on a separate thread in between the time of the first error and the call to retrieve this message.
	details string // contextual informations, thread safe
}

// Code returns the original SQLite error code (or -1 for errors generated by the Go wrapper)
func (e ConnError) Code() Errno {
	return e.code
}

// ExtendedCode returns the SQLite extended error code.
// (See http://www.sqlite.org/c3ref/errcode.html)
// FIXME it might be the case that a second error occurs on a separate thread in between the time of the first error and the call to this method.
func (e ConnError) ExtendedCode() int {
	return int(C.sqlite3_extended_errcode(e.c.db))
}

// Filename returns database file name from which the error comes from.
func (e ConnError) Filename() string {
	return e.c.Filename("main")
}

func (e ConnError) Error() string { // FIXME code.Error() & e.msg are often redundant...
	if len(e.details) > 0 {
		return fmt.Sprintf("%s (%s) (%s)", e.msg, e.details, e.code.Error())
	} else if len(e.msg) > 0 {
		return fmt.Sprintf("%s (%s)", e.msg, e.code.Error())
	}
	return e.code.Error()
}

// Errno enumerates SQLite result codes
type Errno int32

func (e Errno) Error() string {
	var s string
	if e == ErrSpecific {
		s = "wrapper specific error"
	} else {
		s = C.GoString(C.sqlite3_errstr(C.int(e))) // thread safe
	}
	if s == "" {
		return fmt.Sprintf("errno %d", int(e))
	}
	return s
}

// SQLite result codes
const (
	ErrError      = Errno(C.SQLITE_ERROR)      /* SQL error or missing database */
	ErrInternal   = Errno(C.SQLITE_INTERNAL)   /* Internal logic error in SQLite */
	ErrPerm       = Errno(C.SQLITE_PERM)       /* Access permission denied */
	ErrAbort      = Errno(C.SQLITE_ABORT)      /* Callback routine requested an abort */
	ErrBusy       = Errno(C.SQLITE_BUSY)       /* The database file is locked */
	ErrLocked     = Errno(C.SQLITE_LOCKED)     /* A table in the database is locked */
	ErrNoMem      = Errno(C.SQLITE_NOMEM)      /* A malloc() failed */
	ErrReadOnly   = Errno(C.SQLITE_READONLY)   /* Attempt to write a readonly database */
	ErrInterrupt  = Errno(C.SQLITE_INTERRUPT)  /* Operation terminated by sqlite3_interrupt()*/
	ErrIOErr      = Errno(C.SQLITE_IOERR)      /* Some kind of disk I/O error occurred */
	ErrCorrupt    = Errno(C.SQLITE_CORRUPT)    /* The database disk image is malformed */
	ErrNotFound   = Errno(C.SQLITE_NOTFOUND)   /* Unknown opcode in sqlite3_file_control() */
	ErrFull       = Errno(C.SQLITE_FULL)       /* Insertion failed because database is full */
	ErrCantOpen   = Errno(C.SQLITE_CANTOPEN)   /* Unable to open the database file */
	ErrProtocol   = Errno(C.SQLITE_PROTOCOL)   /* Database lock protocol error */
	ErrEmpty      = Errno(C.SQLITE_EMPTY)      /* Database is empty */
	ErrSchema     = Errno(C.SQLITE_SCHEMA)     /* The database schema changed */
	ErrTooBig     = Errno(C.SQLITE_TOOBIG)     /* String or BLOB exceeds size limit */
	ErrConstraint = Errno(C.SQLITE_CONSTRAINT) /* Abort due to constraint violation */
	ErrMismatch   = Errno(C.SQLITE_MISMATCH)   /* Data type mismatch */
	ErrMisuse     = Errno(C.SQLITE_MISUSE)     /* Library used incorrectly */
	ErrNolfs      = Errno(C.SQLITE_NOLFS)      /* Uses OS features not supported on host */
	ErrAuth       = Errno(C.SQLITE_AUTH)       /* Authorization denied */
	ErrFormat     = Errno(C.SQLITE_FORMAT)     /* Auxiliary database format error */
	ErrRange      = Errno(C.SQLITE_RANGE)      /* 2nd parameter to sqlite3_bind out of range */
	ErrNotDB      = Errno(C.SQLITE_NOTADB)     /* File opened that is not a database file */
	//Notice        = Errno(C.SQLITE_NOTICE)     /* Notifications from sqlite3_log() */
	//Warning       = Errno(C.SQLITE_WARNING)    /* Warnings from sqlite3_log() */

	Row         = Errno(C.SQLITE_ROW)  /* sqlite3_step() has another row ready */
	Done        = Errno(C.SQLITE_DONE) /* sqlite3_step() has finished executing */
	ErrSpecific = Errno(-1)            /* Wrapper specific error */
)

func (c *Conn) error(rv C.int, details ...string) error {
	if c == nil {
		return errors.New("nil sqlite database")
	}
	if rv == C.SQLITE_OK {
		return nil
	}
	err := ConnError{c: c, code: Errno(rv), msg: C.GoString(C.sqlite3_errmsg(c.db))}
	if len(details) > 0 {
		err.details = details[0]
	}
	return err
}

func (c *Conn) specificError(msg string, a ...interface{}) error {
	return ConnError{c: c, code: ErrSpecific, msg: fmt.Sprintf(msg, a...)}
}

// LastError returns the error for the most recent failed sqlite3_* API call associated with a database connection.
// (See http://sqlite.org/c3ref/errcode.html)
// FIXME it might be the case that a second error occurs on a separate thread in between the time of the first error and the call to this method.
func (c *Conn) LastError() error {
	if c == nil {
		return errors.New("nil sqlite database")
	}
	errorCode := C.sqlite3_errcode(c.db)
	if errorCode == C.SQLITE_OK {
		return nil
	}
	return ConnError{c: c, code: Errno(errorCode), msg: C.GoString(C.sqlite3_errmsg(c.db))}
}

// Conn represents a database connection handle.
// (See http://sqlite.org/c3ref/sqlite3.html)
type Conn struct {
	db              *C.sqlite3
	stmtCache       *cache
	authorizer      *sqliteAuthorizer
	busyHandler     *sqliteBusyHandler
	profile         *sqliteProfile
	progressHandler *sqliteProgressHandler
	trace           *sqliteTrace
	commitHook      *sqliteCommitHook
	rollbackHook    *sqliteRollbackHook
	updateHook      *sqliteUpdateHook
	udfs            map[string]*sqliteFunction
	modules         map[string]*sqliteModule
	timeUsed        time.Time
	nTransaction    uint8
	// DefaultTimeLayout specifies the layout used to persist time ("2006-01-02 15:04:05.000Z07:00" by default).
	// When set to "", time is persisted as integer (unix time).
	// Using type alias implementing the Scanner/Valuer interfaces is suggested...
	DefaultTimeLayout string
	// ScanNumericalAsTime tells the driver to try to parse column with NUMERIC affinity as time.Time (using the DefaultTimeLayout)
	ScanNumericalAsTime bool
}

// Version returns the run-time library version number
// (See http://sqlite.org/c3ref/libversion.html)
func Version() string {
	p := C.sqlite3_libversion()
	return C.GoString(p)
}

// VersionNumber returns the run-time library version number as 300X00Y
// (See http://sqlite.org/c3ref/libversion.html)
func VersionNumber() int32 {
	return int32(C.sqlite3_libversion_number())
}

// OpenFlag enumerates flags for file open operations
type OpenFlag int32

// Flags for file open operations
const (
	OpenReadOnly     OpenFlag = C.SQLITE_OPEN_READONLY
	OpenReadWrite    OpenFlag = C.SQLITE_OPEN_READWRITE
	OpenCreate       OpenFlag = C.SQLITE_OPEN_CREATE
	OpenURI          OpenFlag = C.SQLITE_OPEN_URI
	OpenNoMutex      OpenFlag = C.SQLITE_OPEN_NOMUTEX
	OpenFullMutex    OpenFlag = C.SQLITE_OPEN_FULLMUTEX
	OpenSharedCache  OpenFlag = C.SQLITE_OPEN_SHAREDCACHE
	OpenPrivateCache OpenFlag = C.SQLITE_OPEN_PRIVATECACHE
)

// Open opens a new database connection.
// ":memory:" for memory db,
// "" for temp file db
//
// (See sqlite3_open_v2: http://sqlite.org/c3ref/open.html)
func Open(filename string, flags ...OpenFlag) (*Conn, error) {
	return OpenVfs(filename, "", flags...)
}

// OpenVfs opens a new database with a specified virtual file system.
func OpenVfs(filename string, vfsname string, flags ...OpenFlag) (*Conn, error) {
	if C.sqlite3_threadsafe() == 0 {
		return nil, errors.New("sqlite library was not compiled for thread-safe operation")
	}
	var openFlags int
	if len(flags) > 0 {
		for _, flag := range flags {
			openFlags |= int(flag)
		}
	} else {
		openFlags = C.SQLITE_OPEN_FULLMUTEX | C.SQLITE_OPEN_READWRITE | C.SQLITE_OPEN_CREATE
	}

	var db *C.sqlite3
	cname := C.CString(filename)
	defer C.free(unsafe.Pointer(cname))
	var vfs *C.char
	if len(vfsname) > 0 {
		vfs = C.CString(vfsname)
		defer C.free(unsafe.Pointer(vfs))
	}
	rv := C.sqlite3_open_v2(cname, &db, C.int(openFlags), vfs)
	if rv != C.SQLITE_OK {
		err := OpenError{
			Code:     Errno(rv),
			Filename: filename,
		}
		if db != nil { // try to extract further details from db...
			err.ExtendedCode = int(C.sqlite3_extended_errcode(db))
			err.Msg = C.GoString(C.sqlite3_errmsg(db))
			C.sqlite3_close(db)
			return nil, err
		}
		return nil, err
	}
	if db == nil {
		return nil, errors.New("sqlite succeeded without returning a database")
	}
	c := &Conn{db: db, stmtCache: newCache(), DefaultTimeLayout: "2006-01-02 15:04:05.000Z07:00"}
	if os.Getenv("SQLITE_DEBUG") != "" {
		//c.SetAuthorizer(authorizer, c.db)
		c.Trace(trace, "TRACE")
		//c.SetCacheSize(0)
	}

	return c, nil
}

/*
func authorizer(d interface{}, action Action, arg1, arg2, dbName, triggerName string) Auth {
	fmt.Fprintf(os.Stderr, "%p: %v, %s, %s, %s, %s\n", d, action, arg1, arg2, dbName, triggerName)
	return AuthOk
}
*/
func trace(d interface{}, sql string) {
	fmt.Fprintf(os.Stderr, "%s: %s\n", d, sql)
}

// BusyTimeout sets a busy timeout and clears any previously set handler.
// If duration is zero or negative, turns off busy handler.
// (See http://sqlite.org/c3ref/busy_timeout.html)
func (c *Conn) BusyTimeout(d time.Duration) error {
	c.busyHandler = nil
	return c.error(C.sqlite3_busy_timeout(c.db, C.int(d/time.Millisecond)), "Conn.BusyTimeout")
}

// Readonly determines if a database is read-only.
// (See http://sqlite.org/c3ref/db_readonly.html)
func (c *Conn) Readonly(dbName string) (bool, error) {
	cname := C.CString(dbName)
	rv := C.sqlite3_db_readonly(c.db, cname)
	C.free(unsafe.Pointer(cname))
	if rv == -1 {
		return false, c.specificError("%q is not the name of a database", dbName)
	}
	return rv == 1, nil
}

// Filename returns the filename for a database connection.
// (See http://sqlite.org/c3ref/db_filename.html)
func (c *Conn) Filename(dbName string) string {
	cname := C.CString(dbName)
	defer C.free(unsafe.Pointer(cname))
	return C.GoString(C.sqlite3_db_filename(c.db, cname))
}

// Exec prepares and executes one or many parameterized statement(s) (separated by semi-colon).
// Don't use it with SELECT or anything that returns data.
func (c *Conn) Exec(cmd string, args ...interface{}) error {
	for len(cmd) > 0 {
		s, err := c.prepare(cmd)
		if err != nil {
			return err
		} else if s.stmt == nil {
			// this happens for a comment or white-space
			cmd = s.tail
			continue
		}
		var subargs []interface{}
		count := s.BindParameterCount()
		if len(s.tail) > 0 && len(args) >= count {
			subargs = args[:count]
			args = args[count:]
		} else {
			subargs = args
		}
		err = s.Exec(subargs...)
		if err != nil {
			s.finalize()
			return err
		}
		if err = s.finalize(); err != nil {
			return err
		}
		cmd = s.tail
	}
	return nil
}

// ExecDml helps executing DML statement:
// (1) it binds the specified args,
// (2) it executes the statement,
// (3) it returns the number of rows that were changed or inserted or deleted.
func (c *Conn) ExecDml(cmd string, args ...interface{}) (changes int, err error) {
	s, err := c.Prepare(cmd)
	if err != nil {
		return -1, err
	}
	defer s.Finalize()
	return s.ExecDml(args...)
}

// Insert is like ExecDml but returns the autoincremented rowid.
func (c *Conn) Insert(cmd string, args ...interface{}) (rowid int64, err error) {
	n, err := c.ExecDml(cmd, args...)
	if err != nil {
		return -1, err
	}
	if n == 0 { // No change => no insert...
		return -1, nil
	}
	return c.LastInsertRowid(), nil
}

// Select helps executing SELECT statement:
// (1) it binds the specified args,
// (2) it steps on the rows returned,
// (3) it delegates scanning to a callback function.
// The callback function is invoked for each result row coming out of the statement.
func (c *Conn) Select(query string, rowCallbackHandler func(s *Stmt) error, args ...interface{}) error {
	s, err := c.Prepare(query)
	if err != nil {
		return err
	}
	defer s.Finalize()
	return s.Select(rowCallbackHandler, args...)
}

// SelectByID helps executing SELECT statement that is expected to return only one row.
// Args are for scanning (not binding).
// Returns false if there is no matching row.
// No check is done to ensure that no more than one row is returned by the statement.
func (c *Conn) SelectByID(query string, id interface{}, args ...interface{}) (found bool, err error) {
	s, err := c.Prepare(query, id)
	if err != nil {
		return false, err
	}
	defer s.Finalize()
	return s.SelectOneRow(args...)
}

// Exists returns true if the specified query returns at least one row.
func (c *Conn) Exists(query string, args ...interface{}) (bool, error) {
	s, err := c.Prepare(query, args...)
	if err != nil {
		return false, err
	}
	defer s.Finalize()
	ok, err := s.Next()
	if err != nil {
		return false, err
	}
	if s.ColumnCount() == 0 {
		return false, s.specificError("don't use Exists with query that returns no data such as %q", query)
	}
	return ok, nil
}

// OneValue is used with SELECT that returns only one row with only one column.
// Returns io.EOF when there is no row.
// No check is performed to ensure that there is no more than one row.
func (c *Conn) OneValue(query string, value interface{}, args ...interface{}) error {
	s, err := c.Prepare(query, args...)
	if err != nil {
		return err
	}
	defer s.Finalize()
	b, err := s.Next()
	if err != nil {
		return err
	} else if !b {
		if s.ColumnCount() == 0 {
			return s.specificError("don't use OneValue with query that returns no data such as %q", query)
		}
		return io.EOF
	}
	return s.Scan(value)
}

// Changes returns the number of database rows that were changed or inserted or deleted by the most recently completed SQL statement on the database connection.
// If a separate thread makes changes on the same database connection while Changes() is running then the value returned is unpredictable and not meaningful.
// (See http://sqlite.org/c3ref/changes.html)
func (c *Conn) Changes() int {
	return int(C.sqlite3_changes(c.db))
}

// TotalChanges returns the number of row changes caused by INSERT, UPDATE or DELETE statements since the database connection was opened.
// (See http://sqlite.org/c3ref/total_changes.html)
func (c *Conn) TotalChanges() int {
	return int(C.sqlite3_total_changes(c.db))
}

// LastInsertRowid returns the rowid of the most recent successful INSERT into the database.
// If a separate thread performs a new INSERT on the same database connection while the LastInsertRowid() function is running and thus changes the last insert rowid, then the value returned by LastInsertRowid() is unpredictable and might not equal either the old or the new last insert rowid.
// (See http://sqlite.org/c3ref/last_insert_rowid.html)
func (c *Conn) LastInsertRowid() int64 {
	return int64(C.sqlite3_last_insert_rowid(c.db))
}

// Interrupt interrupts a long-running query.
// (See http://sqlite.org/c3ref/interrupt.html)
func (c *Conn) Interrupt() {
	C.sqlite3_interrupt(c.db)
}

// GetAutocommit tests for auto-commit mode.
// (See http://sqlite.org/c3ref/get_autocommit.html)
func (c *Conn) GetAutocommit() bool {
	return C.sqlite3_get_autocommit(c.db) != 0
}

// TransactionType enumerates the different transaction behaviors
// See Conn.BeginTransaction
type TransactionType uint8

// Transaction types
const (
	Deferred  TransactionType = 0
	Immediate TransactionType = 1
	Exclusive TransactionType = 2
)

// Begin begins a transaction in deferred mode.
// (See http://www.sqlite.org/lang_transaction.html)
func (c *Conn) Begin() error {
	return c.BeginTransaction(Deferred)
}

// BeginTransaction begins a transaction of the specified type.
// (See http://www.sqlite.org/lang_transaction.html)
func (c *Conn) BeginTransaction(t TransactionType) error {
	if t == Deferred {
		return c.FastExec("BEGIN")
	} else if t == Immediate {
		return c.FastExec("BEGIN IMMEDIATE")
	} else if t == Exclusive {
		return c.FastExec("BEGIN EXCLUSIVE")
	}
	panic(fmt.Sprintf("Unsupported transaction type: '%#v'", t))
}

// Commit commits transaction.
// It is strongly discouraged to defer Commit without checking the error returned.
func (c *Conn) Commit() error {
	// Although there are situations when it is possible to recover and continue a transaction,
	// it is considered a best practice to always issue a ROLLBACK if an error is encountered.
	// In situations when SQLite was already forced to roll back the transaction and has returned to autocommit mode,
	// the ROLLBACK will do nothing but return an error that can be safely ignored.
	err := c.FastExec("COMMIT")
	if err != nil && !c.GetAutocommit() {
		c.Rollback()
	}
	return err
}

// Rollback rollbacks transaction
func (c *Conn) Rollback() error {
	return c.FastExec("ROLLBACK")
}

// Transaction is used to execute a function inside an SQLite database transaction.
// The transaction is committed when the function completes (with no error),
// or it rolls back if the function fails.
// If the transaction occurs within another transaction (only one that is started using this method) a Savepoint is created.
// Two errors may be returned: the first is the one returned by the f function,
// the second is the one returned by begin/commit/rollback.
// (See http://sqlite.org/tclsqlite.html#transaction)
func (c *Conn) Transaction(t TransactionType, f func(c *Conn) error) error {
	var err error
	if c.nTransaction == 0 {
		err = c.BeginTransaction(t)
	} else {
		err = c.Savepoint(strconv.Itoa(int(c.nTransaction)))
	}
	if err != nil {
		return err
	}
	c.nTransaction++
	defer func() {
		c.nTransaction--
		if err != nil {
			_, ko := err.(*ConnError)
			if c.nTransaction == 0 || ko {
				c.Rollback()
			} else {
				if rerr := c.RollbackSavepoint(strconv.Itoa(int(c.nTransaction))); rerr != nil {
					Log(-1, rerr.Error())
				} else if rerr := c.ReleaseSavepoint(strconv.Itoa(int(c.nTransaction))); rerr != nil {
					Log(-1, rerr.Error())
				}
			}
		} else {
			if c.nTransaction == 0 {
				err = c.Commit()
			} else {
				err = c.ReleaseSavepoint(strconv.Itoa(int(c.nTransaction)))
			}
			if err != nil {
				c.Rollback()
			}
		}
	}()
	err = f(c)
	return err
}

// Savepoint starts a new transaction with a name.
// (See http://sqlite.org/lang_savepoint.html)
func (c *Conn) Savepoint(name string) error {
	return c.FastExec(Mprintf("SAVEPOINT %Q", name))
}

// ReleaseSavepoint causes all savepoints back to and including the most recent savepoint with a matching name to be removed from the transaction stack.
// (See http://sqlite.org/lang_savepoint.html)
func (c *Conn) ReleaseSavepoint(name string) error {
	return c.FastExec(Mprintf("RELEASE %Q", name))
}

// RollbackSavepoint reverts the state of the database back to what it was just before the corresponding SAVEPOINT.
// (See http://sqlite.org/lang_savepoint.html)
func (c *Conn) RollbackSavepoint(name string) error {
	return c.FastExec(Mprintf("ROLLBACK TO SAVEPOINT %Q", name))
}

/*
func (c *Conn) exec(cmd string) error {
	s, err := c.prepare(cmd)
	if err != nil {
		return err
	}
	defer s.finalize()
	rv := C.sqlite3_step(s.stmt)
	if Errno(rv) != Done { // this check cannot be done with sqlite3_exec
		return s.error(rv, "Conn.exec(%q)", cmd)
	}
	return nil
}
*/

// FastExec executes one or many non-parameterized statement(s) (separated by semi-colon) with no control and no stmt cache.
func (c *Conn) FastExec(sql string) error {
	sqlstr := C.CString(sql)
	err := c.error(C.sqlite3_exec(c.db, sqlstr, nil, nil, nil))
	C.free(unsafe.Pointer(sqlstr))
	return err
}

// Close closes a database connection and any dangling statements.
// (See http://sqlite.org/c3ref/close.html)
func (c *Conn) Close() error {
	if c == nil {
		return errors.New("nil sqlite database")
	}
	if c.db == nil {
		return nil
	}

	c.stmtCache.flush()

	rv := C.sqlite3_close(c.db)

	if rv&0xFF == C.SQLITE_BUSY {
		// Dangling statements
		stmt := C.sqlite3_next_stmt(c.db, nil)
		for stmt != nil {
			if C.sqlite3_stmt_busy(stmt) != 0 {
				Log(C.SQLITE_MISUSE, "Dangling statement (not reset): \""+C.GoString(C.sqlite3_sql(stmt))+"\"")
			} else {
				Log(C.SQLITE_MISUSE, "Dangling statement (not finalize): \""+C.GoString(C.sqlite3_sql(stmt))+"\"")
			}
			C.sqlite3_finalize(stmt)
			stmt = C.sqlite3_next_stmt(c.db, nil)
		}
		rv = C.sqlite3_close(c.db)
	}

	if rv != C.SQLITE_OK {
		Log(int32(rv), "error while closing Conn")
		return c.error(rv, "Conn.Close")
	}
	c.db = nil
	return nil
}

// IsClosed tells if the database connection has been closed.
func (c *Conn) IsClosed() bool {
	return c == nil || c.db == nil
}