package builder

import (
	"bytes"
	"fmt"
	"gitea-mail-templates/tools/upstream"
	"regexp"
	"strings"
)

type actionSpec struct {
	expression, href, text, key string
	args                        string
}

// This is the single alignment layer between reviewed official mail contexts
// and shared controls. Themes never own URLs, translation keys or mail logic.
var actions = map[string]actionSpec{
	"activate":        {expression: "$activate_url", href: "{{$activate_url}}", text: "{{$activate_url}}", key: "mail.activate_account"},
	"activate_email":  {expression: "$activate_url", href: "{{$activate_url}}", text: "{{$activate_url}}", key: "mail.activate_email"},
	"reset_passwd":    {expression: "$recover_url", href: "{{$recover_url}}", text: "{{$recover_url}}", key: "mail.reset_password"},
	"register_notify": {expression: `(printf "%suser/login" AppUrl)`, href: "{{AppUrl}}user/login", text: "{{AppUrl}}user/login", key: "mail.view_it_on", args: " AppName"},
	"team_invite":     {expression: ".InviteURL", href: "{{.InviteURL}}", text: "{{.InviteURL}}", key: "mail.view_it_on", args: " AppName"},
	"collaborator":    {expression: ".Link", key: "mail.view_it_on", args: " AppName"},
	"transfer":        {expression: ".Link", key: "mail.view_it_on", args: " AppName"},
	"release":         {expression: ".Release.HTMLURL", key: "mail.view_it_on", args: " AppName"},
	"workflow_run":    {expression: ".Run.HTMLURL", key: "mail.view_it_on", args: " AppName"},
	"assigned":        {expression: ".Link", key: "mail.view_it_on", args: " AppName"},
	"default":         {expression: ".Link", key: "mail.view_it_on", args: " AppName"},
}

type sourceEdit struct{ before, after string }

// AdaptOfficial leaves notification branches/data accesses upstream-owned;
// only the presentation of the primary action and fallback is reorganized.
// An edit ledger checks action changes before static presentation annotation.
func AdaptOfficial(s *upstream.Snapshot, name string) ([]byte, error) {
	original := string(s.Templates[name])
	source := original
	spec, ok := actions[upstream.TemplateID(name)]
	if !ok {
		return nil, fmt.Errorf("new mail type %s needs framework alignment", name)
	}
	if _, ok := s.Locales["en-US"][spec.key]; !ok {
		return nil, fmt.Errorf("missing framework translation key %s", spec.key)
	}
	control := fmt.Sprintf(`{{template "mail/base/action" (dict "URL" %s "Label" (.locale.Tr %q%s) "Hint" (.locale.Tr "mail.link_not_working_do_paste"))}}`, spec.expression, spec.key, spec.args)
	var edits []sourceEdit
	replace := func(before, after string) error {
		if strings.Count(source, before) != 1 {
			return fmt.Errorf("%s: expected one reviewed action anchor %q", name, before)
		}
		source = strings.Replace(source, before, after, 1)
		edits = append(edits, sourceEdit{before, after})
		return nil
	}
	if spec.href != "" {
		// Search only static markup/action boundaries reviewed for the primary URL.
		pattern := regexp.MustCompile(`<p(?: style="word-break: break-all;")?><a href="` + regexp.QuoteMeta(spec.href) + `">` + regexp.QuoteMeta(spec.text) + `</a></p>`)
		matches := pattern.FindAllString(source, -1)
		if len(matches) != 1 {
			return nil, fmt.Errorf("%s: primary URL anchor changed; review framework adapter", name)
		}
		if err := replace(matches[0], control); err != nil {
			return nil, err
		}
		hint := `<p>{{.locale.Tr "mail.link_not_working_do_paste"}}</p>`
		if strings.Contains(source, hint) {
			if err := replace(hint, ""); err != nil {
				return nil, err
			}
		}
	} else {
		// These official bodies already contain their primary link in prose.
		// The extra button/fallback does not replace notification text or links.
		footer := `{{template "mail/base/footer"}}`
		if err := replace(footer, `<div class="framework-extra">`+control+`</div>`+"\n"+footer); err != nil {
			return nil, err
		}
	}
	// Replay the recorded action edits and require an exact output match.
	replay := original
	for _, e := range edits {
		replay = strings.Replace(replay, e.before, e.after, 1)
	}
	if replay != source {
		return nil, fmt.Errorf("unrecorded framework change")
	}
	if !bytes.Equal([]byte(original), s.Templates[name]) {
		return nil, fmt.Errorf("upstream source mutated")
	}
	return paragraphRoles([]byte(source), upstream.TemplateID(name))
}

// Use the established theme classes rather than duplicating their typography
// in generic CSS. Only static paragraph tags outside Go actions are annotated.
func paragraphRoles(data []byte, id string) ([]byte, error) {
	masked, err := MaskActions(data)
	if err != nil {
		return nil, err
	}
	anchors, err := BodyAnchors(masked)
	if err != nil {
		return nil, err
	}
	tags := regexp.MustCompile(`(?i)<p(?:\s[^<>]*?)?>`).FindAllIndex(masked[anchors[0]:anchors[1]], -1)
	type edit struct {
		at    int
		class string
	}
	var edits []edit
	for i, loc := range tags {
		start, end := anchors[0]+loc[0], anchors[0]+loc[1]
		if bytes.Contains(masked[start:end], []byte("class=")) {
			continue
		}
		role := "email-text"
		if i == 0 && id != "activate" && id != "activate_email" {
			role = "email-heading"
		}
		stop := bytes.Index(masked[end:anchors[1]], []byte("</p>"))
		if stop < 0 {
			return nil, fmt.Errorf("unclosed official paragraph")
		}
		content := string(data[end : end+stop])
		for _, key := range []string{"mail.activate_account.text_2", "mail.register_notify.text_2", "mail.register_notify.text_3", "mail.team_invite.text_3"} {
			if strings.Contains(content, `"`+key+`"`) {
				role = "email-subtext"
			}
		}
		edits = append(edits, edit{start + 2, role})
	}
	result := bytes.Clone(data)
	for i := len(edits) - 1; i >= 0; i-- {
		e := edits[i]
		result = append(append(append([]byte{}, result[:e.at]...), []byte(` class="`+e.class+`"`)...), result[e.at:]...)
	}
	return result, nil
}