// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>

package cli

import (
	"bufio"
	"fmt"
	"regexp"
	"strconv"
	"strings"
)

var _ = fmt.Print

/*
Create an [Option] from a string. Syntax is::

	--option-name, --option-alias, -s
	type: string
	dest: destination
	choices: choice1, choice2, choice 3
	depth: 0
	Help text on multiple lines. Indented lines are peserved as indented blocks. Blank lines
	are preserved as blank lines. #placeholder_for_formatting# is replaced by the empty string.

Available types are: string, str, list, int, float, count, bool-set, bool-reset, choices
The default dest is the first --option-name which must be a long option.
If choices are specified type is set to choices automatically.
If depth is negative option is added to all subcommands. If depth is positive option is added to sub-commands upto
the specified depth.
Set the help text to "!" to have an option hidden.
*/
func OptionFromString(entries ...string) (*Option, error) {
	if mpat == nil {
		mpat = regexp.MustCompile("^([a-z]+)=(.+)")
	}
	ans := Option{
		values_from_cmdline:        make([]string, 0, 1),
		parsed_values_from_cmdline: make([]interface{}, 0, 1),
	}
	scanner := bufio.NewScanner(strings.NewReader(strings.Join(entries, "\n")))
	in_help := false
	prev_indent := 0
	help := strings.Builder{}
	help.Grow(2048)

	indent_of_line := func(x string) int {
		return len(x) - len(strings.TrimLeft(x, " \n\t\v\f"))
	}

	set_default := func(x string) {
		if ans.Default == "" {
			ans.Default = x
		}
	}

	for scanner.Scan() {
		line := scanner.Text()
		if ans.Aliases == nil {
			if strings.HasPrefix(line, "--") {
				parts := strings.Split(line, " ")
				ans.Name = strings.ReplaceAll(parts[0], "-", "_")
				ans.Aliases = make([]Alias, 0, len(parts))
				for i, x := range parts {
					ans.Aliases[i] = Alias{NameWithoutHyphens: strings.TrimLeft(x, "-"), IsShort: !strings.HasPrefix(x, "--")}
				}
			}
		} else if in_help {
			if line != "" {
				current_indent := indent_of_line(line)
				if current_indent > 1 {
					if prev_indent == 0 {
						help.WriteString("\n")
					} else {
						line = strings.TrimSpace(line)
					}
				}
				prev_indent = current_indent
				if !strings.HasSuffix(help.String(), "\n") {
					help.WriteString(" ")
				}
				help.WriteString(line)
			} else {
				prev_indent = 0
				help.WriteString("\n")
				if !strings.HasSuffix(help.String(), "::") {
					help.WriteString("\n")
				}
			}
		} else {
			matches := mpat.FindStringSubmatch(line)
			if matches == nil {
				continue
			}
			k, v := matches[1], matches[2]
			switch k {
			case "choices":
				parts := strings.Split(v, ",")
				ans.Choices = make(map[string]bool, len(parts))
				ans.OptionType = StringOption
				for i, x := range parts {
					x = strings.TrimSpace(x)
					ans.Choices[x] = true
					if i == 0 && ans.Default == "" {
						ans.Default = x
					}
				}
			case "default":
				ans.Default = v
			case "dest":
				ans.Name = v
			case "depth":
				depth, err := strconv.ParseInt(v, 0, 0)
				if err != nil {
					return nil, err
				}
				ans.Depth = int(depth)
			case "condition", "completion":
			default:
				return nil, fmt.Errorf("Unknown option metadata key: %s", k)
			case "type":
				switch v {
				case "choice", "choices":
					ans.OptionType = StringOption
				case "int":
					ans.OptionType = IntegerOption
					set_default("0")
				case "float":
					ans.OptionType = FloatOption
					set_default("0")
				case "count":
					ans.OptionType = CountOption
					set_default("0")
				case "bool-set":
					ans.OptionType = BoolOption
					set_default("false")
				case "bool-reset":
					ans.OptionType = BoolOption
					set_default("true")
					for _, a := range ans.Aliases {
						a.IsUnset = true
					}
				case "list":
					ans.IsList = true
					fallthrough
				case "str", "string":
					ans.OptionType = StringOption
				default:
					return nil, fmt.Errorf("Unknown option type: %s", v)
				}
			}
		}
	}
	ans.HelpText = help.String()
	ans.Hidden = ans.HelpText == "!"
	pval, err := ans.parse_value(ans.Default)
	if err != nil {
		return nil, err
	}
	ans.parsed_default = pval
	if ans.IsList {
		ans.parsed_default = []string{}
	}
	return &ans, nil
}