package wasmplugin

import (
	"regexp"

	experimental "github.com/corazawaf/coraza/v3/experimental/regexp"
	"github.com/corazawaf/coraza/v3/experimental/regexp/regexptypes"
)

func init() {
	experimental.SetRegexpCompiler(Compile)
}

type lazyRegexp struct {
	matchStringFn           func(string) bool
	findStringSubmatchFn    func(string) []string
	findAllStringSubmatchFn func(string, int) [][]string
	subexpNamesFn           func() []string
	matchFn                 func([]byte) bool
	stringFn                func() string
}

var _ regexptypes.Regexp = (*lazyRegexp)(nil)

func (r *lazyRegexp) MatchString(s string) bool {
	return r.matchStringFn(s)
}

func (r *lazyRegexp) FindStringSubmatch(s string) []string {
	return r.findStringSubmatchFn(s)
}

func (r *lazyRegexp) FindAllStringSubmatch(s string, n int) [][]string {
	return r.findAllStringSubmatchFn(s, n)
}

func (r *lazyRegexp) SubexpNames() []string {
	return r.subexpNamesFn()
}

func (r *lazyRegexp) Match(b []byte) bool {
	return r.matchFn(b)
}

func (r *lazyRegexp) String() string {
	return r.stringFn()
}

func Compile(expr string) (regexptypes.Regexp, error) {
	// Check if the expression is valid and can be compiled
	if _, err := regexp.Compile(expr); err != nil {
		return nil, err
	}

	lre := &lazyRegexp{}

	lre.matchStringFn = func(s string) bool {
		compileAndReassign(expr, lre)
		return lre.matchStringFn(s)
	}

	lre.findStringSubmatchFn = func(s string) []string {
		compileAndReassign(expr, lre)
		return lre.findStringSubmatchFn(s)
	}

	lre.findAllStringSubmatchFn = func(s string, n int) [][]string {
		compileAndReassign(expr, lre)
		return lre.findAllStringSubmatchFn(s, n)
	}

	lre.subexpNamesFn = func() []string {
		compileAndReassign(expr, lre)
		return lre.subexpNamesFn()
	}

	lre.matchFn = func(b []byte) bool {
		compileAndReassign(expr, lre)
		return lre.matchFn(b)
	}

	lre.stringFn = func() string {
		compileAndReassign(expr, lre)
		return lre.stringFn()
	}

	return lre, nil
}

func compileAndReassign(expr string, lre *lazyRegexp) {
	re := regexp.MustCompile(expr)

	lre.matchStringFn = re.MatchString
	lre.findStringSubmatchFn = re.FindStringSubmatch
	lre.findAllStringSubmatchFn = re.FindAllStringSubmatch
	lre.subexpNamesFn = re.SubexpNames
	lre.matchFn = re.Match
	lre.stringFn = re.String
}