package libpod

import (
	"database/sql"
	"encoding/json"
	"io/ioutil"
	"os"
	"path/filepath"
	"time"

	"github.com/containers/storage"
	spec "github.com/opencontainers/runtime-spec/specs-go"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"

	// Use SQLite backend for sql package
	_ "github.com/mattn/go-sqlite3"
)

// Checks that the DB configuration matches the runtime's configuration
func checkDB(db *sql.DB, r *Runtime) (err error) {
	// Create a table to hold runtime information
	// TODO: Include UID/GID mappings
	const runtimeTable = `
        CREATE TABLE runtime(
            Id              INTEGER NOT NULL PRIMARY KEY,
            SchemaVersion   INTEGER NOT NULL,
            StaticDir       TEXT    NOT NULL,
            TmpDir          TEXT    NOT NULL,
            RunRoot         TEXT    NOT NULL,
            GraphRoot       TEXT    NOT NULL,
            GraphDriverName TEXT    NOT NULL,
            CHECK (Id=0)
        );
        `
	const fillRuntimeTable = `INSERT INTO runtime VALUES (
            ?, ?, ?, ?, ?, ?, ?
        );`

	const selectRuntimeTable = `SELECT SchemaVersion,
                                           StaticDir,
                                           TmpDir,
                                           RunRoot,
                                           GraphRoot,
                                           GraphDriverName
                                    FROM runtime WHERE id=0;`

	const checkRuntimeExists = "SELECT name FROM sqlite_master WHERE type='table' AND name='runtime';"

	tx, err := db.Begin()
	if err != nil {
		return errors.Wrapf(err, "error beginning database transaction")
	}
	defer func() {
		if err != nil {
			if err2 := tx.Rollback(); err2 != nil {
				logrus.Errorf("Error rolling back transaction to check runtime table: %v", err2)
			}
		}

	}()

	row := tx.QueryRow(checkRuntimeExists)
	var table string
	if err := row.Scan(&table); err != nil {
		// There is no runtime table
		// Create and populate the runtime table
		if err == sql.ErrNoRows {
			if _, err := tx.Exec(runtimeTable); err != nil {
				return errors.Wrapf(err, "error creating runtime table in database")
			}

			_, err := tx.Exec(fillRuntimeTable,
				0,
				DBSchema,
				r.config.StaticDir,
				r.config.TmpDir,
				r.config.StorageConfig.RunRoot,
				r.config.StorageConfig.GraphRoot,
				r.config.StorageConfig.GraphDriverName)
			if err != nil {
				return errors.Wrapf(err, "error populating runtime table in database")
			}

			if err := tx.Commit(); err != nil {
				return errors.Wrapf(err, "error committing runtime table transaction in database")
			}

			return nil
		}

		return errors.Wrapf(err, "error checking for presence of runtime table in database")
	}

	// There is a runtime table
	// Retrieve its contents
	var (
		schemaVersion   int
		staticDir       string
		tmpDir          string
		runRoot         string
		graphRoot       string
		graphDriverName string
	)

	row = tx.QueryRow(selectRuntimeTable)
	err = row.Scan(
		&schemaVersion,
		&staticDir,
		&tmpDir,
		&runRoot,
		&graphRoot,
		&graphDriverName)
	if err != nil {
		return errors.Wrapf(err, "error retrieving runtime information from database")
	}

	// Compare the information in the database against our runtime config
	if schemaVersion != DBSchema {
		return errors.Wrapf(ErrDBBadConfig, "database schema version %d does not match our schema version %d",
			schemaVersion, DBSchema)
	}
	if staticDir != r.config.StaticDir {
		return errors.Wrapf(ErrDBBadConfig, "database static directory %s does not match our static directory %s",
			staticDir, r.config.StaticDir)
	}
	if tmpDir != r.config.TmpDir {
		return errors.Wrapf(ErrDBBadConfig, "database temp directory %s does not match our temp directory %s",
			tmpDir, r.config.TmpDir)
	}
	if runRoot != r.config.StorageConfig.RunRoot {
		return errors.Wrapf(ErrDBBadConfig, "database runroot directory %s does not match our runroot directory %s",
			runRoot, r.config.StorageConfig.RunRoot)
	}
	if graphRoot != r.config.StorageConfig.GraphRoot {
		return errors.Wrapf(ErrDBBadConfig, "database graph root directory %s does not match our graph root directory %s",
			graphRoot, r.config.StorageConfig.GraphRoot)
	}
	if graphDriverName != r.config.StorageConfig.GraphDriverName {
		return errors.Wrapf(ErrDBBadConfig, "database runroot directory %s does not match our runroot directory %s",
			graphDriverName, r.config.StorageConfig.GraphDriverName)
	}

	if err := tx.Commit(); err != nil {
		return errors.Wrapf(err, "error committing runtime table transaction in database")
	}

	return nil
}

// Performs database setup including by not limited to initializing tables in
// the database
func prepareDB(db *sql.DB) (err error) {
	// TODO create pod tables
	// TODO add Pod ID to CreateStaticContainer as a FOREIGN KEY referencing podStatic(Id)
	// TODO add ctr shared namespaces information - A separate table, probably? So we can FOREIGN KEY the ID
	// TODO schema migration might be necessary and should be handled here
	// TODO maybe make a port mappings table instead of JSONing the array and storing it?
	// TODO prepared statements for common queries for performance

	// Enable foreign keys in SQLite
	if _, err := db.Exec("PRAGMA foreign_keys = ON;"); err != nil {
		return errors.Wrapf(err, "error enabling foreign key support in database")
	}

	// Create a table for unchanging container data
	const createCtr = `
        CREATE TABLE IF NOT EXISTS containers(
            Id              TEXT    NOT NULL PRIMARY KEY,
            Name            TEXT    NOT NULL UNIQUE,
            Pod             TEXT,

            RootfsImageID   TEXT    NOT NULL,
            RootfsImageName TEXT    NOT NULL,
            ImageVolumes    INTEGER NOT NULL,
            ReadOnly        INTEGER NOT NULL,
            ShmDir          TEXT    NOT NULL,
            ShmSize         INTEGER NOT NULL,
            StaticDir       TEXT    NOT NULL,
            Mounts          TEXT    NOT NULL,

            Privileged      INTEGER NOT NULL,
            NoNewPrivs      INTEGER NOT NULL,
            ProcessLabel    TEXT    NOT NULL,
            MountLabel      TEXT    NOT NULL,
            User            TEXT    NOT NULL,

            IPCNsCtr        TEXT,
            MountNsCtr      TEXT,
            NetNsCtr        TEXT,
            PIDNsCtr        TEXT,
            UserNsCtr       TEXT,
            UTSNsCtr        TEXT,
            CgroupNsCtr     TEXT,

            CreateNetNS     INTEGER NOT NULL,
            DNSServer       TEXT    NOT NULL,
            DNSSearch       TEXT    NOT NULL,
            DNSOption       TEXT    NOT NULL,
            HostAdd         TEXT    NOT NULL,

            Stdin           INTEGER NOT NULL,
            LabelsJSON      TEXT    NOT NULL,
            StopSignal      INTEGER NOT NULL,
            StopTimeout     INTEGER NOT NULL,
            CreatedTime     TEXT    NOT NULL,
            CgroupParent    TEXT    NOT NULL,

            CHECK (ImageVolumes IN (0, 1)),
            CHECK (ReadOnly IN (0, 1)),
            CHECK (SHMSize>=0),
            CHECK (Privileged IN (0, 1)),
            CHECK (NoNewPrivs IN (0, 1)),
            CHECK (CreateNetNS IN (0, 1)),
            CHECK (Stdin IN (0, 1)),
            CHECK (StopSignal>=0),
            FOREIGN KEY (Id)          REFERENCES containerState(Id) DEFERRABLE INITIALLY DEFERRED
            FOREIGN KEY (Pod)         REFERENCES pod(Id)            DEFERRABLE INITIALLY DEFERRED,
            FOREIGN KEY (IPCNsCtr)    REFERENCES containers(Id)     DEFERRABLE INITIALLY DEFERRED,
            FOREIGN KEY (MountNsCtr)  REFERENCES containers(Id)     DEFERRABLE INITIALLY DEFERRED,
            FOREIGN KEY (NetNsCtr)    REFERENCES containers(Id)     DEFERRABLE INITIALLY DEFERRED,
            FOREIGN KEY (PIDNsCtr)    REFERENCES containers(Id)     DEFERRABLE INITIALLY DEFERRED,
            FOREIGN KEY (UserNsCtr)   REFERENCES containers(Id)     DEFERRABLE INITIALLY DEFERRED,
            FOREIGN KEY (UTSNsCtr)    REFERENCES containers(Id)     DEFERRABLE INITIALLY DEFERRED,
            FOREIGN KEY (CgroupNsCtr) REFERENCES containers(Id)     DEFERRABLE INITIALLY DEFERRED
        );
        `

	// Create a table for changing container state
	const createCtrState = `
        CREATE TABLE IF NOT EXISTS containerState(
            Id           TEXT    NOT NULL PRIMARY KEY,
            State        INTEGER NOT NULL,
            ConfigPath   TEXT    NOT NULL,
            RunDir       TEXT    NOT NULL,
            Mountpoint   TEXT    NOT NULL,
            StartedTime  TEXT    NUT NULL,
            FinishedTime TEXT    NOT NULL,
            ExitCode     INTEGER NOT NULL,
            OomKilled    INTEGER NOT NULL,
            Pid          INTEGER NOT NULL,
            NetNSPath    TEXT    NOT NULL,
            IPAddress    TEXT    NOT NULL,
            SubnetMask   TEXT    NOT NULL,

            CHECK (State>0),
            CHECK (OomKilled IN (0, 1)),
            FOREIGN KEY (Id) REFERENCES containers(Id) DEFERRABLE INITIALLY DEFERRED
        );
        `

	// Create a table for pod config
	const createPod = `
        CREATE TABLE IF NOT EXISTS pod(
            Id     TEXT NOT NULL PRIMARY KEY,
            Name   TEXT NOT NULL UNIQUE,
            Labels TEXT NOT NULL
        );
        `

	// Create the tables
	tx, err := db.Begin()
	if err != nil {
		return errors.Wrapf(err, "error beginning database transaction")
	}
	defer func() {
		if err != nil {
			if err2 := tx.Rollback(); err2 != nil {
				logrus.Errorf("Error rolling back transaction to create tables: %v", err2)
			}
		}

	}()

	if _, err := tx.Exec(createCtr); err != nil {
		return errors.Wrapf(err, "error creating containers table in database")
	}
	if _, err := tx.Exec(createCtrState); err != nil {
		return errors.Wrapf(err, "error creating container state table in database")
	}
	if _, err := tx.Exec(createPod); err != nil {
		return errors.Wrapf(err, "error creating pods table in database")
	}

	if err := tx.Commit(); err != nil {
		return errors.Wrapf(err, "error committing table creation transaction in database")
	}

	return nil
}

// Get filename for OCI spec on disk
func getSpecPath(specsDir, id string) string {
	return filepath.Join(specsDir, id)
}

// Get filename for container port mappings on disk
func getPortsPath(specsDir, id string) string {
	return filepath.Join(specsDir, id+"_ports")
}

// Convert a bool into SQL-readable format
func boolToSQL(b bool) int {
	if b {
		return 1
	}

	return 0
}

// Convert a null string from SQL-readable format
func stringFromNullString(s sql.NullString) string {
	if s.Valid {
		return s.String
	}
	return ""
}

// Convert a string to a SQL nullable string
func stringToNullString(s string) sql.NullString {
	if s == "" {
		return sql.NullString{}
	}
	return sql.NullString{
		String: s,
		Valid:  true,
	}
}

// Convert a bool from SQL-readable format
func boolFromSQL(i int) bool {
	return i != 0
}

// Convert a time.Time into SQL-readable format
func timeToSQL(t time.Time) string {
	return t.Format(time.RFC3339Nano)
}

// Convert a SQL-readable time back to a time.Time
func timeFromSQL(s string) (time.Time, error) {
	return time.Parse(time.RFC3339Nano, s)
}

// Interface to abstract sql.Rows and sql.Row so they can both be used
type scannable interface {
	Scan(dest ...interface{}) error
}

// Read a single container from a single row result in the database
func (s *SQLState) ctrFromScannable(row scannable) (*Container, error) {
	var (
		id   string
		name string
		pod  sql.NullString

		rootfsImageID   string
		rootfsImageName string
		imageVolumes    int
		readOnly        int
		shmDir          string
		shmSize         int64
		staticDir       string
		mounts          string

		privileged   int
		noNewPrivs   int
		processLabel string
		mountLabel   string
		user         string

		ipcNsCtrNullStr    sql.NullString
		mountNsCtrNullStr  sql.NullString
		netNsCtrNullStr    sql.NullString
		pidNsCtrNullStr    sql.NullString
		userNsCtrNullStr   sql.NullString
		utsNsCtrNullStr    sql.NullString
		cgroupNsCtrNullStr sql.NullString

		createNetNS   int
		dnsServerJSON string
		dnsSearchJSON string
		dnsOptionJSON string
		hostAddJSON   string

		stdin             int
		labelsJSON        string
		stopSignal        uint
		stopTimeout       uint
		createdTimeString string
		cgroupParent      string

		state              int
		configPath         string
		runDir             string
		mountpoint         string
		startedTimeString  string
		finishedTimeString string
		exitCode           int32
		oomKilled          int
		pid                int
		netNSPath          string
		ipAddress          string
		subnetMask         string
	)

	err := row.Scan(
		&id,
		&name,
		&pod,

		&rootfsImageID,
		&rootfsImageName,
		&imageVolumes,
		&readOnly,
		&shmDir,
		&shmSize,
		&staticDir,
		&mounts,

		&privileged,
		&noNewPrivs,
		&processLabel,
		&mountLabel,
		&user,

		&ipcNsCtrNullStr,
		&mountNsCtrNullStr,
		&netNsCtrNullStr,
		&pidNsCtrNullStr,
		&userNsCtrNullStr,
		&utsNsCtrNullStr,
		&cgroupNsCtrNullStr,

		&createNetNS,
		&dnsServerJSON,
		&dnsSearchJSON,
		&dnsOptionJSON,
		&hostAddJSON,

		&stdin,
		&labelsJSON,
		&stopSignal,
		&stopTimeout,
		&createdTimeString,
		&cgroupParent,

		&state,
		&configPath,
		&runDir,
		&mountpoint,
		&startedTimeString,
		&finishedTimeString,
		&exitCode,
		&oomKilled,
		&pid,
		&netNSPath,
		&ipAddress,
		&subnetMask)
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, ErrNoSuchCtr
		}

		return nil, errors.Wrapf(err, "error parsing database row into container")
	}

	ctr := new(Container)
	ctr.config = new(ContainerConfig)
	ctr.state = new(containerState)

	ctr.config.ID = id
	ctr.config.Name = name
	ctr.config.Pod = stringFromNullString(pod)

	ctr.config.RootfsImageID = rootfsImageID
	ctr.config.RootfsImageName = rootfsImageName
	ctr.config.ImageVolumes = boolFromSQL(imageVolumes)
	ctr.config.ReadOnly = boolFromSQL(readOnly)
	ctr.config.ShmDir = shmDir
	ctr.config.ShmSize = shmSize
	ctr.config.StaticDir = staticDir

	ctr.config.Privileged = boolFromSQL(privileged)
	ctr.config.NoNewPrivs = boolFromSQL(noNewPrivs)
	ctr.config.ProcessLabel = processLabel
	ctr.config.MountLabel = mountLabel
	ctr.config.User = user

	ctr.config.IPCNsCtr = stringFromNullString(ipcNsCtrNullStr)
	ctr.config.MountNsCtr = stringFromNullString(mountNsCtrNullStr)
	ctr.config.NetNsCtr = stringFromNullString(netNsCtrNullStr)
	ctr.config.PIDNsCtr = stringFromNullString(pidNsCtrNullStr)
	ctr.config.UserNsCtr = stringFromNullString(userNsCtrNullStr)
	ctr.config.UTSNsCtr = stringFromNullString(utsNsCtrNullStr)
	ctr.config.CgroupNsCtr = stringFromNullString(cgroupNsCtrNullStr)

	ctr.config.CreateNetNS = boolFromSQL(createNetNS)

	ctr.config.Stdin = boolFromSQL(stdin)
	ctr.config.StopSignal = stopSignal
	ctr.config.StopTimeout = stopTimeout
	ctr.config.CgroupParent = cgroupParent

	ctr.state.State = ContainerStatus(state)
	ctr.state.ConfigPath = configPath
	ctr.state.RunDir = runDir
	ctr.state.Mountpoint = mountpoint
	ctr.state.ExitCode = exitCode
	ctr.state.OOMKilled = boolFromSQL(oomKilled)
	ctr.state.PID = pid
	ctr.state.IPAddress = ipAddress
	ctr.state.SubnetMask = subnetMask

	// TODO should we store this in the database separately instead?
	if ctr.state.Mountpoint != "" {
		ctr.state.Mounted = true
	}

	if err := json.Unmarshal([]byte(mounts), &ctr.config.Mounts); err != nil {
		return nil, errors.Wrapf(err, "error parsing container %s mounts JSON", id)
	}

	if err := json.Unmarshal([]byte(dnsServerJSON), &ctr.config.DNSServer); err != nil {
		return nil, errors.Wrapf(err, "error parsing container %s DNS server JSON", id)
	}

	if err := json.Unmarshal([]byte(dnsSearchJSON), &ctr.config.DNSSearch); err != nil {
		return nil, errors.Wrapf(err, "error parsing container %s DNS search JSON", id)
	}

	if err := json.Unmarshal([]byte(dnsOptionJSON), &ctr.config.DNSOption); err != nil {
		return nil, errors.Wrapf(err, "error parsing container %s DNS option JSON", id)
	}

	if err := json.Unmarshal([]byte(hostAddJSON), &ctr.config.HostAdd); err != nil {
		return nil, errors.Wrapf(err, "error parsing container %s DNS server JSON", id)
	}

	labels := make(map[string]string)
	if err := json.Unmarshal([]byte(labelsJSON), &labels); err != nil {
		return nil, errors.Wrapf(err, "error parsing container %s labels JSON", id)
	}
	ctr.config.Labels = labels

	createdTime, err := timeFromSQL(createdTimeString)
	if err != nil {
		return nil, errors.Wrapf(err, "error parsing container %s created time", id)
	}
	ctr.config.CreatedTime = createdTime

	startedTime, err := timeFromSQL(startedTimeString)
	if err != nil {
		return nil, errors.Wrapf(err, "error parsing container %s started time", id)
	}
	ctr.state.StartedTime = startedTime

	finishedTime, err := timeFromSQL(finishedTimeString)
	if err != nil {
		return nil, errors.Wrapf(err, "error parsing container %s finished time", id)
	}
	ctr.state.FinishedTime = finishedTime

	// Join the network namespace, if there is one
	if netNSPath != "" {
		netNS, err := joinNetNS(netNSPath)
		if err != nil {
			return nil, errors.Wrapf(err, "error joining network namespace for container %s", id)
		}
		ctr.state.NetNS = netNS
	}

	ctr.valid = true
	ctr.runtime = s.runtime

	// Open and set the lockfile
	lockPath := filepath.Join(s.lockDir, id)
	lock, err := storage.GetLockfile(lockPath)
	if err != nil {
		return nil, errors.Wrapf(err, "error retrieving lockfile for container %s", id)
	}
	ctr.lock = lock

	// Retrieve the spec from disk
	ociSpec := new(spec.Spec)
	specPath := getSpecPath(s.specsDir, id)
	fileContents, err := ioutil.ReadFile(specPath)
	if err != nil {
		return nil, errors.Wrapf(err, "error reading container %s OCI spec", id)
	}
	if err := json.Unmarshal(fileContents, ociSpec); err != nil {
		return nil, errors.Wrapf(err, "error parsing container %s OCI spec", id)
	}
	ctr.config.Spec = ociSpec

	// Retrieve the ports from disk
	// They may not exist - if they don't, this container just doesn't have ports
	portPath := getPortsPath(s.specsDir, id)
	_, err = os.Stat(portPath)
	if err != nil {
		if !os.IsNotExist(err) {
			return nil, errors.Wrapf(err, "error stating container %s JSON ports", id)
		}
	}
	if err == nil {
		// The file exists, read it
		fileContents, err := ioutil.ReadFile(portPath)
		if err != nil {
			return nil, errors.Wrapf(err, "error reading container %s JSON ports", id)
		}
		if err := json.Unmarshal(fileContents, &ctr.config.PortMappings); err != nil {
			return nil, errors.Wrapf(err, "error parsing container %s JSON ports", id)
		}
	}

	return ctr, nil
}