package cmd

import (
	"fmt"
	"errors"
	"reflect"
	"strconv"
	"strings"
) 

func ListDatastores(args []string, display bool) error {
	/***************************************************************
	/   Filter datastores by names given on command line
	/**************************************************************/
	for _, d := range args {
		cmd := fmt.Sprintf("zfs list -p -H -o name,used,available,referenced %s", d)
		out, err := executeCommand(cmd)
		if err != nil {
			if strings.HasSuffix(err.Error(), "No such file or directory") {
				return errors.New(fmt.Sprintf("Datastore does not exist: %s", d))
			} else {
				return errors.New(fmt.Sprintf("Error executing command %s: %v; command returned: %s\n", cmd, err, out))
			}
		}
		
		fields := strings.Fields(out)
		if len(fields) < 4 {
			return errors.New(fmt.Sprintf("Error parsing output of \"%s\": Not enough fields", cmd))
		}
		u, _ := strconv.ParseUint(fields[1], 10, 64)
		a, _ := strconv.ParseUint(fields[2], 10, 64)
		r, _ := strconv.ParseUint(fields[3], 10, 64)
		ds := Datastore{Name: d[1:], Mountpoint: d, ZFSDataset: fields[0], Used: u, Referenced: r, Available: a}
		
		err = loadDefaultsForDatastore(&ds)
		if err != nil {
			return err
		}
		
		gDatastores = append(gDatastores, ds)
	}
	
	fields := strings.Split(gDisplayDColumns, ",")

	if true == display {
		/***************************************************************
		/   Sort datastores
		/     We support 3 sort criteria max
		/**************************************************************/
		if len(gSortDSFields) > 0 && gSortDSFields != "none" {		
			ds := initDatastoreSortStruct()

			// The way we manage criteria quantity is not very elegant...
			var fct1, fct2, fct3 *reflect.Value
			for i, c := range strings.Split(gSortDSFields, ",") {
				var fctName string
				if strings.HasPrefix(c, "-") {
					fctName = fmt.Sprintf("%sDec", strings.Replace(c, "-", "", 1))
				} else { // Par defaut (pas de prefix +/-) on considere un tri incremental
					fctName = fmt.Sprintf("%sInc", strings.Replace(c, "+", "", 1))
				}

				// Get function by its name
				fct, _, err := getStructFieldValue(ds, fctName)
				
				if err != nil {
					fieldName := strings.Replace(strings.Replace(c, "-", "", 1), "+", "", 1)
					return errors.New(fmt.Sprintf("ERROR getting DatastoreSort struct field %s. Please check the field name: %s\n", fctName, fieldName))
				}
				switch i + 1 {
				case 1:
					fct1 = fct
				case 2:
					fct2 = fct
				case 3:
					fct3 = fct
				}
			}

			switch len(strings.Split(gSortDSFields, ",")) {
			case 1:
				DatastoresOrderedBy(fct1.Interface().(datastoreLessFunc)).Sort(gDatastores)
			case 2:
				DatastoresOrderedBy(fct1.Interface().(datastoreLessFunc), fct2.Interface().(datastoreLessFunc)).Sort(gDatastores)
			case 3:
				DatastoresOrderedBy(fct1.Interface().(datastoreLessFunc), fct2.Interface().(datastoreLessFunc), fct3.Interface().(datastoreLessFunc)).Sort(gDatastores)
			}
		}
		displayDatastoresFields(gDatastores, fields)
	}
	
	return nil
}

/********************************************************************************
 * Load jails default config from $datastore/defaults.json
 *******************************************************************************/
func loadDefaultsForDatastore(ds *Datastore) error {
	jc, err := getJailConfig(fmt.Sprintf("%s/defaults.json", ds.Mountpoint))
	if err != nil {
		return err
	}

	ds.DefaultJailConfig = jc
	//gDefaultConfig = append(gDefaultConfig, jc)

	return nil
}