package lexers

import (
	. "github.com/alecthomas/chroma" // nolint
	"strings"
)

// HTTP lexer.
var HTTP = Register(httpBodyContentTypeLexer(MustNewLexer(
	&Config{
		Name:         "HTTP",
		Aliases:      []string{"http"},
		Filenames:    []string{},
		MimeTypes:    []string{},
		NotMultiline: true,
		DotAll:       true,
	},
	Rules{
		"root": {
			{`(GET|POST|PUT|DELETE|HEAD|OPTIONS|TRACE|PATCH)( +)([^ ]+)( +)(HTTP)(/)(1\.[01])(\r?\n|\Z)`, ByGroups(NameFunction, Text, NameNamespace, Text, KeywordReserved, Operator, LiteralNumber, Text), Push("headers")},
			{`(HTTP)(/)(1\.[01])( +)(\d{3})( +)([^\r\n]+)(\r?\n|\Z)`, ByGroups(KeywordReserved, Operator, LiteralNumber, Text, LiteralNumber, Text, NameException, Text), Push("headers")},
		},
		"headers": {
			{`([^\s:]+)( *)(:)( *)([^\r\n]+)(\r?\n|\Z)`, EmitterFunc(httpHeaderBlock), nil},
			{`([\t ]+)([^\r\n]+)(\r?\n|\Z)`, EmitterFunc(httpContinuousHeaderBlock), nil},
			{`\r?\n`, Text, Push("content")},
		},
		"content": {
			{`.+`, EmitterFunc(httpContentBlock), nil},
		},
	},
)))

func httpContentBlock(groups []string, lexer Lexer) Iterator {
	tokens := []*Token{
		{Generic, groups[0]},
	}
	return Literator(tokens...)

}

func httpHeaderBlock(groups []string, lexer Lexer) Iterator {
	tokens := []*Token{
		{Name, groups[1]},
		{Text, groups[2]},
		{Operator, groups[3]},
		{Text, groups[4]},
		{Literal, groups[5]},
		{Text, groups[6]},
	}
	return Literator(tokens...)
}

func httpContinuousHeaderBlock(groups []string, lexer Lexer) Iterator {
	tokens := []*Token{
		{Text, groups[1]},
		{Literal, groups[2]},
		{Text, groups[3]},
	}
	return Literator(tokens...)
}

func httpBodyContentTypeLexer(lexer Lexer) Lexer { return &httpBodyContentTyper{lexer} }

type httpBodyContentTyper struct{ Lexer }

func (d *httpBodyContentTyper) Tokenise(options *TokeniseOptions, text string) (Iterator, error) {
	var contentType string
	var isContentType bool
	var subIterator Iterator

	it, err := d.Lexer.Tokenise(options, text)
	if err != nil {
		return nil, err
	}

	return func() *Token {
		for token := it(); token != nil; token = it() {
			switch {
			case token.Type == Name && strings.ToLower(token.Value) == "content-type":
				{
					isContentType = true
				}
			case token.Type == Literal && isContentType:
				{
					contentType = strings.TrimSpace(token.Value)
					pos := strings.Index(contentType, ";")
					if pos > 0 {
						contentType = strings.TrimSpace(contentType[:pos])
					}
				}
			case token.Type == Generic && contentType != "":
				{
					lexer := MatchMimeType(contentType)

					// application/calendar+xml can be treated as application/xml
					// if there's not a better match.
					if lexer == nil && strings.Contains(contentType, "+") {
						slashPos := strings.Index(contentType, "/")
						plusPos := strings.LastIndex(contentType, "+")
						contentType = contentType[:slashPos+1] + contentType[plusPos+1:]
						lexer = MatchMimeType(contentType)
					}

					if lexer == nil {
						token.Type = Text
					} else {
						subIterator, err = lexer.Tokenise(nil, token.Value)
						if err != nil {
							panic(err)
						}
						return nil
					}
				}

			}

			return token
		}

		if subIterator != nil {
			for token := subIterator(); token != nil; token = subIterator() {
				return token
			}
		}
		return nil

	}, nil
}