package cmd

import (
	"os"
	"fmt"
	"log"
	"errors"
	"reflect"
	"strings"
	"io/ioutil"
	"gocage/jail"
	"encoding/json"
	"github.com/spf13/viper"
)


// Recurse into structure, returning reflect.Value of wanted field.
//  Nested fields are named with a dot (ex "MyStruct.MyField")
func getStructFieldValue(parentStruct interface{}, fieldName string) (reflect.Value, string, error) {
	v := reflect.ValueOf(parentStruct)

	if v.Kind() == reflect.Ptr {
		v = v.Elem()
	}

	if false {
		for i := 0 ; i < v.NumField(); i++ {
			f := v.Field(i)
			if f.Kind() == reflect.String {
				fmt.Printf("%v=%v\n", v.Type().Field(i).Name, f.Interface())
			}
		}
	}

	if strings.Contains(fieldName, ".") {
		fs := strings.Split(fieldName, ".")
		f := v.FieldByName(fs[0])
		if f.Kind() == reflect.Struct {
			return getStructFieldValue(f.Interface(), strings.Join(fs[1:], "."))
		} else {
			log.Fatalln(fmt.Sprintf("%s is not a struct: %s\n", fs[0], f.Kind().String()))
		}
	} else {
		f := v.FieldByName(fieldName)
		if f.IsValid() {
			return f, fieldName, nil
		} else {
			return v, fieldName, errors.New(fmt.Sprintf("Field not found: %s", fieldName))
		}
	}

	return v, fieldName, nil
}


// TODO : Replace by getStructFieldValue
// Recurse into structure, returning reflect.Value of wanted field.
//  Nested fields are named with a dot (ex "MyStruct.MyField")
func getStructField(parentStruct interface{}, fieldName string) (reflect.Value, string) {
	v := reflect.ValueOf(parentStruct)

	if v.Kind() == reflect.Ptr {
		v = v.Elem()
	}

	if false {
		for i := 0 ; i < v.NumField(); i++ {
			f := v.Field(i)
			if f.Kind() == reflect.String {
				fmt.Printf("%v=%v\n", v.Type().Field(i).Name, f.Interface())
			}
		}
	}

	if strings.Contains(fieldName, ".") {
		fs := strings.Split(fieldName, ".")
		f := v.FieldByName(fs[0])
		if f.Kind() == reflect.Struct {
			return getStructField(f.Interface(), strings.Join(fs[1:], "."))
		} else {
			log.Fatalln(fmt.Sprintf("%s is not a struct: %s\n", fs[0], f.Kind().String()))
		}
	}

	return v, fieldName
}


/* Pretty display of jails field
   Fields to show are given in a string array parameter
   Ex. : displayJails(["Name", "JID", "RootPath"])
*/
func displayStructFields(jails []Jail, valsToDisplay []string) {
	/* A line is defined by :
		Nr of fields
		For each field :
			Its name
			Its max length
			Its value
	*/
	type Field struct {
		Name	string
		MaxLen	int
		Value	string
	}

	type Line []Field

	type Output []Line
	var out Output

	//fmt.Printf("%d fields in a %d items structure\n", len(valsToDisplay), len(jails))

	// Browse structure to get max length and values
	for _, j := range jails {
		// Have to use a pointer, else reflect.Value.Elem() will panic : https://pkg.go.dev/reflect#Value.Elem
		tj := &j
		
		line := make([]Field, len(valsToDisplay))
		for i, f := range valsToDisplay {
			a, f := getStructField(tj, f)

			field := Field {
				Name: f,
			}
			if a.FieldByName(f).IsValid() {
				// For now this just contains this item length, will adjust later
				//  We need to divide length by number of items in string fields (because we can have more than 1 ip4_addr)
				if reflect.TypeOf(a.FieldByName(f).Interface()).Kind() == reflect.String {
					itnr := len(strings.Split(string(a.FieldByName(f).Interface().(string)), ","))
					field.MaxLen = len(fmt.Sprintf("%v", a.FieldByName(f).Interface())) / itnr
				} else {
					field.MaxLen = len(fmt.Sprintf("%v", a.FieldByName(f).Interface()))
				}
				field.Value = fmt.Sprintf("%v", a.FieldByName(f).Interface())
			} else {
				fmt.Printf("Invalid field name: %s\n", f)
			}
			line[i] = field
			
		}
		out = append(out, line)
	}

	if len(out) == 0 {
		fmt.Printf("Nothing to see here!\n")
		return
	}

	// Get real maximum length
	maxlen := make([]int, len(valsToDisplay))
	for i := 0; i< len(valsToDisplay); i++ {
		maxlen[i] = len(valsToDisplay[i])
	}
	for _, l := range out {
		for i, f := range l {
			if f.MaxLen > maxlen[i] {
				maxlen[i] = f.MaxLen
			}
		}
	}

	// Align maxlen to the real maximum length
	for io, l := range out {
		for ii, _ := range l {
			// We need to access slice by index if we want to modify content
			out[io][ii].MaxLen = maxlen[ii]
		}
	}

	totalLen := 0
	// For each field, add separator and 2 blank spaces 
	for _, f := range out[0] {
		totalLen += f.MaxLen + 3
	}
	// Then add starting delimiter 
	totalLen += 1

	Debug := false
	if Debug == true {
		for _, f := range out[0] {
			fmt.Printf("%s max length : %d\n", f.Name, f.MaxLen)
		}
	}

	// Lets draw things on the screen!
	// First, headers: 1st separator line
	for i, f := range out[0] {
		if i == 0 {	fmt.Printf("+")	}
		for i := 0 ; i < f.MaxLen+2 ; i++ {	fmt.Printf("=")	}
		fmt.Printf("+")
	}
	fmt.Printf("\n")


	//  Column names
	for i, f := range out[0] {
		if i == 0 {
			fmt.Printf("|")
		}
		/* Use vlsToDisplay to get real name (with "Config.")
		fmt.Printf(" %s", f.Name)
		for i := len(f.Name)+1 ; i < f.MaxLen+1 ; i++ {  */
		fmt.Printf(" %s", valsToDisplay[i])
		for i := len(valsToDisplay[i])+1 ; i < f.MaxLen+1 ; i++ {
			fmt.Printf(" ")
		}
		fmt.Printf(" |")
	}
	//  Finally separator line
	fmt.Printf("\n")
	for i, f := range out[0] {
		if i == 0 {	fmt.Printf("+")	}
		for i := 0 ; i < f.MaxLen+2 ; i++ {	fmt.Printf("=")	}
		fmt.Printf("+")
	}
	fmt.Printf("\n")

	// Then display data
	//  Loop through lines
	for _, l := range out {
		
		// Loop through fields
		//  In case we need to add a line for a 2nd IP, or whatever object
		var supplines = make(map[string]string)
		for i, f := range l {
			if i == 0 {
				fmt.Printf("|")
			}
			// Special cases of value displaying
			if f.Name == "JID" && f.Value == "0" {
				fmt.Printf("  ")
			} else if f.Name == "Ip4_addr" {
				ia := strings.Split(f.Value, ",")
				// If we have more than 1 value we need to finish this line, and store value for writing at the end of line loop
				for i, inter := range ia {
					if i > 0 {
						supplines[f.Name] = inter
					} else {
						fmt.Printf(" %s", inter)
					}
				}
				//fmt.Printf(" %s", strings.Split(strings.Split(f.Value, "|")[1], "/")[0])
			} else {
				fmt.Printf(" %s", f.Value)
			}
			// Complete with spaces to the max length
			for i := len(f.Value)+1 ; i < f.MaxLen+1 ; i++ {
				fmt.Printf(" ")
			}
			fmt.Printf(" |")
		}
		// Draw supplementary lines
		if len(supplines) > 0 {
			for i, f := range l {
				if i == 0 {
					fmt.Printf("\n|")
				}
				// Overwrite value in this scope
				v, exists := supplines[f.Name]
				if exists {
					fmt.Printf(" %s", v)
				} else {
					// 1st option : Do not redisplay precedent line values
					fmt.Printf(" ")
					// 2nd option : Redisplay precedenet line values
					//fmt.Printf(" %s", f.Value)
				}
				// Complete with spaces to the max length
				for i := len(v)+1 ; i < f.MaxLen+1 ; i++ {
					fmt.Printf(" ")
				}
				fmt.Printf(" |")
			}
		}
		// Draw line separator between jails
		if !gNoLineSep {
			fmt.Printf("\n")
			for i, f := range out[0] {
				if i == 0 {	fmt.Printf("+")	}
				for i := 0 ; i < f.MaxLen+2 ; i++ {	fmt.Printf("-")	}
				fmt.Printf("+")
			}
		}
		fmt.Printf("\n")
	}
	if gNoLineSep {
		for i, f := range out[0] {
			if i == 0 {	fmt.Printf("+")	}
			for i := 0 ; i < f.MaxLen+2 ; i++ {	fmt.Printf("-")	}
			fmt.Printf("+")
		}
	}
	
	fmt.Printf("\n")
}


/* Get Jails from datastores. Store config and running metadata into gJails global var */
func ListJails(args []string, display bool) {
	fields := strings.Split(gDisplayColumns, ",")

	for _, d := range viper.GetStringSlice("datastore") {
		listJailsFromDatastore(d)
	}

	// This is the structure we will filter, then display
	var jails []Jail

	/************************************************************************************
	/   Filter jails with "filter" options
	/***********************************************************************************/
	if len(gFilterJails) > 0 && gFilterJails != "none" {
		flts := make(map[string]string)
		for _, flt := range strings.Split(gFilterJails, ",") {
			sa := strings.Split(flt, "=")
			if len(sa) != 2 {
				fmt.Printf("Invalid format for filter %s\n", gFilterJails)
				return
			}
			flts[sa[0]] = sa[1]
		}

		if len(flts) > 0 {
			// Browse global gJails array to get filtered results
			for _, j := range gJails {
				for key, val := range flts {
					v, _, err := getStructFieldValue(&j, key)
					if err != nil {
						fmt.Printf("ERROR: Field %s not found\n", key)
						return
					}
					if strings.EqualFold(fmt.Sprintf("%v", v.Interface()), val) {
						jails = append(jails, j)
					}
				}
			}
		}
	} else {
		jails = gJails
	}


	/************************************************************************************
	/   Filter jails by names given on command line
	/***********************************************************************************/
	if len(args) > 0 {
		var js []Jail
		for _, a := range args {
			for _, j := range jails {
				if j.Name == a {
					js = append(js, j)
					break
				}
			}
		}
		jails = js
	}

	/************************************************************************************
	/   Sort jails
	/     We support 3 sort criteria max
	/***********************************************************************************/
	if len(gSortFields) > 0 {
		js := initSortStruct()

		// The way we manage criteria quantity is not very elegant...
		var fct1, fct2, fct3 reflect.Value
		for i, c := range strings.Split(gSortFields, ",") {
			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(js, fctName)
			if err != nil {
				fieldName := strings.Replace(strings.Replace(c, "-", "", 1), "+", "", 1)
				fmt.Printf("ERROR getting JailSort struct field %s. Please check the field name: %s\n", fctName, fieldName)
				return
			}
			switch i+1 {
				case 1:	fct1 = fct
				case 2: fct2 = fct
				case 3: fct3 = fct
			}
		}

		switch len(strings.Split(gSortFields, ",")) {
			case 1:
				OrderedBy(fct1.Interface().(lessFunc)).Sort(jails)
			case 2:
				OrderedBy(fct1.Interface().(lessFunc), fct2.Interface().(lessFunc)).Sort(jails)
			case 3:
				OrderedBy(fct1.Interface().(lessFunc), fct2.Interface().(lessFunc), fct3.Interface().(lessFunc)).Sort(jails)
		}
	}

	/************************************************************************************
	/   Finally, display jails
	/***********************************************************************************/
	if display {
		displayStructFields(jails, fields)
	}
}


func listJailsFromDatastore(datastore string) {
	fileInfo, err := os.Stat(datastore)
	if err != nil { log.Fatalln(fmt.Sprintf("Unable to access %s, check path and/or rights", datastore)) }
	if fileInfo.IsDir() == false { log.Fatalln(fmt.Sprintf("%s is not a directory", datastore)) }

	// A datastore have to contain a "jails" directory
	jailsDir := fmt.Sprintf("%s/jails", datastore)
	fileInfo, err = os.Stat(jailsDir)
	if err != nil { log.Fatalln(fmt.Sprintf("Unable to access %s, check path and/or rights", jailsDir)) }
	if fileInfo.IsDir() == false { log.Fatalln(fmt.Sprintf("%s is not a directory", jailsDir)) }

	listJailsFromDirectory(jailsDir)
}


func listJailsFromDirectory(dir string) ([]Jail) {
	files, err := ioutil.ReadDir(dir)
	if err != nil { log.Fatalln(fmt.Sprintf("Unable to browse %s, check path and/or rights", dir)) }

	for _, fi := range files {
		if fi.IsDir() == true {

		// 1. Get conf from config.json
			jailConfPath := fmt.Sprintf("%s/%s/%s", dir, fi.Name(), "config.json")
			jailConf, err := getJailConfig(jailConfPath)
			if err != nil { log.Println("ERROR reading jail config for %s", jailConfPath) }
	
		// 2. Build jail object from config
			jailRootPath := fmt.Sprintf("%s/%s/%s", dir, fi.Name(), "root")
			j := Jail{
				Name: jailConf.Host_hostname,
				Config: jailConf,
				ConfigPath: jailConfPath,
				RootPath: jailRootPath,
				Running: false,
			}

		// 3. Add current running informations
			rjails, err := jail.GetJails()
			if err != nil { log.Fatalln("Unable to list running jails") }
			for _, rj := range rjails {
				if rj.Path == j.RootPath {
					j.JID = rj.Jid
					j.Running = true
					j.InternalName = rj.Name
					break
				}
			}
	
/* This op take some 600ms for ~40 jails :^( */
			out, err := executeCommand(fmt.Sprintf("zfs list -H -o name %s", j.RootPath))
			if err != nil {
				fmt.Printf("ERROR getting dataset from %s: %s\n", j.RootPath, err.Error())
			} else {
				j.Zpool = strings.Split(strings.TrimSuffix(out, "\n"), "/")[0]
			}

			gJails = append(gJails, j)
		}
	}

	return gJails
}


func getJailConfig(jailConfigPath string) (JailConfig, error) {
	content, err := ioutil.ReadFile(jailConfigPath)
	if err != nil { log.Fatalln(fmt.Sprintf("Unable to read %s, check path and/or rights", jailConfigPath)) }

	var jc JailConfig
	err = json.Unmarshal([]byte(content), &jc)
	if err != nil { log.Fatalln(fmt.Sprintf("Error occured during unmarshaling %s: %s", jailConfigPath, err.Error())) }

	return jc, err
}