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

// expander-base-funcs.go
package text

import (
	"strings"
)

func ExFuncDefault(ctx ExpanderContext, varValue string, args []string) (result string, err error) {

	if len(varValue) > 0 {
		result = varValue
	} else if len(args) > 0 {
		if len(args) == 1 {
			result = args[0]
		} else if len(args) > 1 {
			result = strings.Join(args[1:], args[0])
		}
	}
	return
}

func ExFuncUpper(ctx ExpanderContext, varValue string, args []string) (result string, err error) {
	result = strings.ToUpper(varValue)
	return
}

func ExFuncLower(ctx ExpanderContext, varValue string, args []string) (result string, err error) {
	result = strings.ToLower(varValue)
	return
}

func ExFuncJoin(ctx ExpanderContext, varValue string, args []string) (result string, err error) {
	if len(args) > 0 {
		result = strings.Join(args[1:], args[0])
	}
	return
}

func ExFuncSet(ctx ExpanderContext, varValue string, args []string) (result string, err error) {
	if len(args) == 1 {
		result = ctx.SetVar(args[0], varValue)
	} else if len(args) > 1 {
		result = ctx.SetVar(args[0], args[1])
	} else {
		result = varValue
	}
	return
}

func ExFuncGet(ctx ExpanderContext, varValue string, args []string) (result string, err error) {
	var found bool
	if len(args) == 0 {
		result, found = ctx.GetVar(varValue)
	} else {
		result, found = ctx.GetVar(args[0])
		if !found && len(args) > 1 {
			result = args[1]
		}
	}
	return
}

func ExFuncTrimSuffix(ctx ExpanderContext, varValue string, args []string) (result string, err error) {
	if len(args) == 0 {
		if pos := strings.LastIndexByte(varValue, '.'); pos >= 0 {
			result = varValue[:pos]
		}
	} else {
		found := false
		for _, arg := range args {
			if remainder := strings.TrimSuffix(varValue, arg); remainder != varValue {
				result = remainder
				found = true
				break
			}
		}
		if !found {
			result = varValue
		}
	}
	return
}

func AddBaseFuncs(ctx ExpanderContext) ExpanderContext {
	ctx.AddFunc("__default", ExFuncDefault, 0, -1, "Returns the flow value if not empty, else all args joined; first arg is used as separator.")
	ctx.AddFunc("__get", ExFuncGet, 0, 2, "Returns the value of the specified variable (arg1). With no arguments it returns the value of the variable having the flow value as name (same as __get ${.}). Arg2 is the default value. ")
	ctx.AddFunc("__set", ExFuncSet, 1, 2, "Sets the value (arg2 or flow) of the specified variables (arg1).")
	ctx.AddFunc("__join", ExFuncJoin, 1, -1, "Joins its args starting from the second. The first one (arg1) is the separator")
	ctx.AddFunc("__lower", ExFuncLower, 0, 0, "Changes the flow value to lower case.")
	ctx.AddFunc("__upper", ExFuncUpper, 0, 0, "Changes the flow value to upper case.")
	ctx.AddFunc("__trim-suffix", ExFuncTrimSuffix, 1, 1, "Removes the specified suffix (arg1) from the flow.")
	return ctx
}