package cmds

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"text/template"

	"github.com/pobri19/sqlboiler/dbdrivers"
	"github.com/spf13/cobra"
)

// cmdData is used globally by all commands to access the table schema data,
// the database driver and the output file. cmdData is initialized by
// the root SQLBoiler cobra command at run time, before other commands execute.
var cmdData *CmdData

// templates holds a slice of pointers to all templates in the templates directory.
var templates []*template.Template

// SQLBoiler is the root app command
var SQLBoiler = &cobra.Command{
	Use:   "sqlboiler",
	Short: "SQL Boiler generates boilerplate structs and statements",
	Long: "SQL Boiler generates boilerplate structs and statements.\n" +
		`Complete documentation is available at http://github.com/pobri19/sqlboiler`,
}

// init initializes the sqlboiler flags, such as driver, table, and output file.
// It also sets the global preRun hook and postRun hook. Every command will execute
// these hooks before and after running to initialize the shared state.
func init() {
	SQLBoiler.PersistentFlags().StringP("driver", "d", "", "The name of the driver in your config.toml (mandatory)")
	SQLBoiler.PersistentFlags().StringP("table", "t", "", "A comma seperated list of table names")
	SQLBoiler.PersistentFlags().StringP("out", "o", "", "The name of the output file")
	SQLBoiler.PersistentPreRun = sqlBoilerPreRun
	SQLBoiler.PersistentPostRun = sqlBoilerPostRun

	// Initialize the SQLBoiler commands and hook the custom Run functions
	initCommands(SQLBoiler, sqlBoilerCommands, sqlBoilerCommandRuns)
}

// sqlBoilerPostRun cleans up the output file and database connection once
// all commands are finished running.
func sqlBoilerPostRun(cmd *cobra.Command, args []string) {
	cmdData.OutFile.Close()
	cmdData.DBDriver.Close()
}

// sqlBoilerPreRun executes before all commands start running. Its job is to
// initialize the shared state object (cmdData). Initialization tasks include
// assigning the database driver based off the driver flag and opening the database connection,
// retrieving a list of all the tables in the database (if specific tables are not provided
// via a flag), building the table schema for use in the templates, and opening the output file
// handle if one is specified with a flag.
func sqlBoilerPreRun(cmd *cobra.Command, args []string) {
	var err error
	cmdData = &CmdData{}

	// Initialize the cmdData.DBDriver
	initDBDriver()

	// Connect to the driver database
	if err = cmdData.DBDriver.Open(); err != nil {
		errorQuit(fmt.Errorf("Unable to connect to the database: %s", err))
	}

	// Initialize the cmdData.TableNames
	initTableNames()

	// Initialize the cmdData.TablesInfo
	initTablesInfo()

	// Initialize the cmdData.OutFile
	initOutFile()

	// Initialize the templates
	templates, err = initTemplates()
	if err != nil {
		errorQuit(fmt.Errorf("Unable to initialize templates: %s", err))
	}
}

// initDBDriver attempts to set the cmdData DBDriver based off the passed in
// driver flag value. If an invalid flag string is provided the program will exit.
func initDBDriver() {
	// Retrieve driver flag
	driverName := SQLBoiler.PersistentFlags().Lookup("driver").Value.String()
	if driverName == "" {
		errorQuit(errors.New("Must supply a driver flag."))
	}

	// Create a driver based off driver flag
	switch driverName {
	case "postgres":
		cmdData.DBDriver = dbdrivers.NewPostgresDriver(
			cfg.Postgres.User,
			cfg.Postgres.Pass,
			cfg.Postgres.DBName,
			cfg.Postgres.Host,
			cfg.Postgres.Port,
		)
	}

	if cmdData.DBDriver == nil {
		errorQuit(errors.New("An invalid driver name was provided"))
	}
}

// initTableNames will create a string slice out of the passed in table flag value
// if one is provided. If no flag is provided, it will attempt to connect to the
// database to retrieve all "public" table names, and build a slice out of that result.
func initTableNames() {
	// Retrieve the list of tables
	tn := SQLBoiler.PersistentFlags().Lookup("table").Value.String()

	if len(tn) != 0 {
		cmdData.TableNames = strings.Split(tn, ",")
		for i, name := range cmdData.TableNames {
			cmdData.TableNames[i] = strings.TrimSpace(name)
		}
	}

	// If no table names are provided attempt to process all tables in database
	if len(cmdData.TableNames) == 0 {
		// get all table names
		var err error
		cmdData.TableNames, err = cmdData.DBDriver.GetAllTableNames()
		if err != nil {
			errorQuit(fmt.Errorf("Unable to get all table names: %s", err))
		}

		if len(cmdData.TableNames) == 0 {
			errorQuit(errors.New("No tables found in database, migrate some tables first"))
		}
	}
}

// initTablesInfo builds a description of each table (column name, column type)
// and assigns it to cmdData.TablesInfo, the slice of dbdrivers.DBTable slices.
func initTablesInfo() {
	// loop over table Names and build TablesInfo
	for i := 0; i < len(cmdData.TableNames); i++ {
		tInfo, err := cmdData.DBDriver.GetTableInfo(cmdData.TableNames[i])
		if err != nil {
			errorQuit(fmt.Errorf("Unable to get the table info: %s", err))
		}

		cmdData.TablesInfo = append(cmdData.TablesInfo, tInfo)
	}
}

// initOutFile opens a file handle to the file name specified by the out flag.
// If no file name is provided, out will remain nil and future output will be
// piped to Stdout instead of to a file.
func initOutFile() {
	// open the out file filehandle
	outf := SQLBoiler.PersistentFlags().Lookup("out").Value.String()
	if outf != "" {
		var err error
		cmdData.OutFile, err = os.Create(outf)
		if err != nil {
			errorQuit(fmt.Errorf("Unable to obtain output file handle: %s", err))
		}
	}
}

// initTemplates loads all of the template files in the /cmds/templates directory
// and returns a slice of pointers to these templates.
func initTemplates() ([]*template.Template, error) {
	wd, err := os.Getwd()
	if err != nil {
		return nil, err
	}

	pattern := filepath.Join(wd, "/cmds/templates", "*.tpl")
	tpl, err := template.New("").Funcs(sqlBoilerTemplateFuncs).ParseGlob(pattern)

	if err != nil {
		return nil, err
	}

	return tpl.Templates(), err
}

// initCommands loads all of the commands in the sqlBoilerCommands and hooks their run functions.
func initCommands(rootCmd *cobra.Command, commands map[string]*cobra.Command, commandRuns map[string]CobraRunFunc) {
	for _, c := range commands {
		// If there is a commandRun for the command (matched by name)
		// then set the Run hook
		r, ok := commandRuns[c.Name()]
		if ok {
			c.Run = r
		} else {
			c.Run = defaultRun // Load default run if no custom run is found
		}

		// Add the command
		rootCmd.AddCommand(c)
	}
}