// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
// All rights reserved.

// text-util.go
package utils

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"os/user"
	"sort"
	"strings"
	"time"
)

type TextTemplate struct {
	varMap     map[string]string
	UserName   string
	Uid        string
	ProgramDir string
	HomeDir    string
	env        map[string]string
}

func NewTextTemplate(args ...string) (instance *TextTemplate) {
	instance = &TextTemplate{}
	user, err := user.Current()
	if err == nil {
		instance.UserName = user.Username
		instance.HomeDir = user.HomeDir
		instance.Uid = user.Uid
	}

	instance.ProgramDir, _ = GetProgramDirPath()
	instance.varMap = make(map[string]string, 5+len(args))
	instance.initVarMap()

	for _, arg := range args {
		if len(arg) == 0 {
			break
		}
		parts := strings.SplitN(arg, ":", 2)
		if len(parts) == 2 {
			instance.varMap[parts[0]] = parts[1]
		} else {
			instance.varMap[parts[0]] = ""
		}
	}

	instance.env = make(map[string]string)
	for _, v := range os.Environ() {
		parts := strings.SplitN(v, "=", 2)
		instance.env[parts[0]] = parts[1]
	}
	return
}

func (self *TextTemplate) initVarMap() {
	self.varMap["dt"] = "Current timestamp as YYYY-MM-DD_HH-MM-SS"
	self.varMap["ymd"] = "Current date as YYYY-MM-DD"
	self.varMap["hm"] = "Current time as HH-MM"
	self.varMap["h"] = "Current time as HH"
	self.varMap["hms"] = "Current time as HH-MM-SS"
	self.varMap["month"] = "Month name"
	self.varMap["month-num"] = "Month as number (mm)"
	self.varMap["week-day"] = "Week day name"
	self.varMap["week-day-num"] = "Week day as number"
	self.varMap["yesterday"] = "Yesterday date"
	self.varMap["uid"] = self.Uid
	self.varMap["username"] = self.UserName
	self.varMap["home"] = self.HomeDir
	self.varMap["progdir"] = self.ProgramDir
	self.varMap["hostname"], _ = os.Hostname()
}

func (self *TextTemplate) AddVar(name, value string) {
	self.varMap[name] = value
}

// func MakeVarMap() map[string]string {
// 	return map[string]string{
// 		"ymd": "Current date as YYYY-MM-DD",
// 		"hms": "Current time as HH-MM-SS",
// 		// "host":  "Hostname",
// 		"uid":      "UID",
// 		"username": "Username",
// 		"home":     "Home directory",
// 	}
// }

func (self *TextTemplate) updateVarMap() {
	var now = time.Now()

	self.varMap["ymd"] = fmt.Sprintf("%04d-%02d-%02d", now.Year(), now.Month(), now.Day())
	self.varMap["hms"] = fmt.Sprintf("%02d-%02d-%02d", now.Hour(), now.Minute(), now.Second())
	self.varMap["hm"] = fmt.Sprintf("%02d-%02d", now.Hour(), now.Minute())
	self.varMap["h"] = fmt.Sprintf("%02d", now.Hour())
	self.varMap["month"] = now.Format("January")
	self.varMap["month-num"] = fmt.Sprintf("%02d", now.Month())
	self.varMap["week-day-num"] = fmt.Sprintf("%d", 1+now.Weekday())
	self.varMap["week-day"] = now.Format("Monday")
	self.varMap["dt"] = self.varMap["ymd"] + "_" + self.varMap["hms"]

	yday := now.AddDate(0, 0, -1)
	self.varMap["yesterday"] = fmt.Sprintf("%04d-%02d-%02d", yday.Year(), yday.Month(), yday.Day())
	// self.varMap["uid"] = strconv.Itoa(int(self.Uid))
	// self.varMap["uid"] = self.Uid
	// self.varMap["username"] = self.UserName
	// // self.varMap["host"] = self.Hostname
	// self.varMap["home"] = self.HomeDir
}

func (self *TextTemplate) Expand(template string) string {

	self.updateVarMap()

	result := os.Expand(template, func(name string) string {
		value, ok := self.varMap[name]
		if ok {
			return value
		} else {
			return ""
		}
	})

	return result
}

func (self *TextTemplate) ExpandEnv(template string) (result string) {
	if len(template) > 0 {
		self.updateVarMap()
		result = os.Expand(template, func(name string) string {
			value, ok := self.varMap[name]
			if ok {
				return value
			} else {
				return "${" + name + "}"
			}
		})

		// for k, v := range self.varMap {
		// 	self.env[k] = v
		// }

		result = os.ExpandEnv(result)
		// result = os.Expand(result, func(name string) string {
		// 	value, ok := self.env[name]
		// 	if ok {
		// 		return value
		// 	} else {
		// 		return ""
		// 	}
		// })
	}
	return result
}

func (self *TextTemplate) Value(key string) (value string, ok bool) {
	value, ok = self.varMap[key]
	return
}

func (self *TextTemplate) String() string {
	var sb strings.Builder

	keys := make([]string, 0, len(self.varMap))
	for k := range self.varMap {
		keys = append(keys, k)
	}
	sort.Strings(keys)

	for _, k := range keys {
		sb.WriteString(fmt.Sprintf("%s=%#v\n", k, self.varMap[k]))
	}
	// for k, v := range self.varMap {
	// 	sb.WriteString(fmt.Sprintf("%s=%#v\n", k, v))
	// }
	return sb.String()
}

func ParseParamPairsFile(sourceFile string, separator string, hook func(line int, name, value string) (err error)) (err error) {
	var source io.Reader
	if source, err = os.Open(sourceFile); err == nil {
		err = ParseParamPairs(source, separator, hook)
	}
	return
}

func ParseParamPairs(source io.Reader, separator string, hook func(line int, name, value string) (err error)) (err error) {
	var content, sep, name, value []byte
	var sb strings.Builder

	if content, err = ioutil.ReadAll(source); err != nil {
		return
	}

	if len(separator) == 0 {
		sep = []byte{' '}
	} else {
		sep = []byte(separator)
	}
	for lineCount, rawLine := range bytes.Split(content, []byte{'\n'}) {
		rawLine = bytes.TrimSpace(rawLine)
		if len(rawLine) == 0 || rawLine[0] == '#' {
			continue
		}
		parts := bytes.SplitN(rawLine, sep, 2)
		name = bytes.TrimSpace(parts[0])
		if len(parts) > 1 {
			value = bytes.TrimSpace(parts[1])
		} else {
			value = []byte{}
		}
		quoteOn := false
		escMode := false
		sb.Reset()
		for _, c := range value {
			switch c {
			case '"':
				if escMode {
					sb.WriteByte(c)
					escMode = false
				} else {
					quoteOn = !quoteOn
				}
			case '\\':
				if escMode {
					sb.WriteByte(c)
					escMode = false
				} else {
					escMode = true
				}
			case 'n':
				if escMode {
					sb.WriteByte('\n')
					escMode = false
				} else {
					sb.WriteByte(c)
				}
			case 'r':
				if escMode {
					sb.WriteByte('\r')
					escMode = false
				} else {
					sb.WriteByte(c)
				}
			case 't':
				if escMode {
					sb.WriteByte('\t')
					escMode = false
				} else {
					sb.WriteByte(c)
				}
			case '#':
				if quoteOn {
					sb.WriteByte(c)
				} else if escMode {
					sb.WriteByte(c)
					escMode = false
				} else {
					goto endloop
				}
			default:
				if escMode {
					escMode = false
				}
				sb.WriteByte(c)
			}
		}
	endloop:
		if err == nil && quoteOn {
			err = errors.New("unbalanced quotes")
			break
		}
		if err == nil {
			if err = hook(lineCount, string(name), sb.String()); err != nil {
				break
			}
		}
	}
	return
}