feat: redirects screen

- golem15.seo.redirects list and form (UI-SPEC C8): chain rows marked,
  status, match, origin and chain filters, the navigation item lands here
- a field-less extension on the controller refuses a loop with
  redirects.loop on target, answers the chain notice and records history
- the status dropdown posts text, read through RedirectStatus

models/redirect.go

@@ -1,8 +1,10 @@
 package models
 
 import (
+	"fmt"
 	"net/url"
 	"regexp"
+	"strconv"
 	"strings"
 	"time"
 
@@ -16,11 +18,25 @@ const (
 	RedirectRegex   = "regex"
 )
 
+// RedirectStatus is a redirect's HTTP status. The admin form's dropdown
+// posts it as text ("301"), which UnmarshalText reads.
+type RedirectStatus int
+
+// UnmarshalText reads a status written as text.
+func (s *RedirectStatus) UnmarshalText(b []byte) error {
+	n, err := strconv.Atoi(strings.TrimSpace(string(b)))
+	if err != nil {
+		return fmt.Errorf("models: redirect status %q is not a number", b)
+	}
+	*s = RedirectStatus(n)
+	return nil
+}
+
 // The statuses of a redirect (D-16).
 const (
-	Status301 = 301
-	Status302 = 302
-	Status410 = 410
+	Status301 RedirectStatus = 301
+	Status302 RedirectStatus = 302
+	Status410 RedirectStatus = 410
 )
 
 // The query string options of a redirect (D-17).
@@ -46,18 +62,18 @@ const (
 // trailing slash; Query ignores the request's query string or passes it to
 // the target. Origin records who created the rule.
 type Redirect struct {
-	ID            uint       `gorm:"column:id;primaryKey"`
-	Source        string     `gorm:"column:source"`
-	Match         string     `gorm:"column:match"`
-	Target        string     `gorm:"column:target"`
-	Status        int        `gorm:"column:status"`
-	Query         string     `gorm:"column:query"`
-	IgnoreCase    bool       `gorm:"column:ignore_case"`
-	TrailingSlash bool       `gorm:"column:trailing_slash"`
-	Origin        string     `gorm:"column:origin"`
-	Note          string     `gorm:"column:note"`
-	CreatedAt     *time.Time `gorm:"column:created_at"`
-	UpdatedAt     *time.Time `gorm:"column:updated_at"`
+	ID            uint           `gorm:"column:id;primaryKey"`
+	Source        string         `gorm:"column:source"`
+	Match         string         `gorm:"column:match"`
+	Target        string         `gorm:"column:target"`
+	Status        RedirectStatus `gorm:"column:status"`
+	Query         string         `gorm:"column:query"`
+	IgnoreCase    bool           `gorm:"column:ignore_case"`
+	TrailingSlash bool           `gorm:"column:trailing_slash"`
+	Origin        string         `gorm:"column:origin"`
+	Note          string         `gorm:"column:note"`
+	CreatedAt     *time.Time     `gorm:"column:created_at"`
+	UpdatedAt     *time.Time     `gorm:"column:updated_at"`
 }
 
 func (Redirect) TableName() string { return "golem15_seo_redirects" }
@@ -189,3 +205,63 @@ func regexError(err error) string {
 func init() {
 	Register(Redirect{})
 }
+
+// RedirectOrigins are the origins in filter order.
+var RedirectOrigins = []string{OriginManual, OriginSlug, OriginImport, OriginMCP, OriginNotFound}
+
+// The redirects list's filter scopes and the chain filter's values.
+const (
+	FilterRedirectStatus = "FilterRedirectStatus"
+	FilterRedirectMatch  = "FilterRedirectMatch"
+	FilterRedirectOrigin = "FilterRedirectOrigin"
+	FilterRedirectChain  = "FilterRedirectChain"
+	ChainOnly            = "only"
+	ChainHide            = "hide"
+)
+
+// FilterScopes lists the redirects list's filter scopes.
+func (Redirect) FilterScopes() []string {
+	return []string{FilterRedirectStatus, FilterRedirectMatch, FilterRedirectOrigin, FilterRedirectChain}
+}
+
+// chainSQL is true for a redirect whose target is another redirect's
+// source.
+const chainSQL = `EXISTS (SELECT 1 FROM golem15_seo_redirects AS next WHERE next.source = golem15_seo_redirects.target AND next.id <> golem15_seo_redirects.id)`
+
+// FilterScope narrows the redirects list; an unknown value matches
+// nothing.
+func (Redirect) FilterScope(name string, db *gorm.DB, value any) *gorm.DB {
+	if db == nil {
+		return db
+	}
+	s, _ := value.(string)
+	switch name {
+	case FilterRedirectStatus:
+		n, err := strconv.Atoi(s)
+		if err != nil || (n != 301 && n != 302 && n != 410) {
+			return db.Where("1 = 0")
+		}
+		return db.Where("golem15_seo_redirects.status = ?", n)
+	case FilterRedirectMatch:
+		if s != RedirectExact && s != RedirectPattern && s != RedirectRegex {
+			return db.Where("1 = 0")
+		}
+		return db.Where("golem15_seo_redirects.match = ?", s)
+	case FilterRedirectOrigin:
+		for _, o := range RedirectOrigins {
+			if o == s {
+				return db.Where("golem15_seo_redirects.origin = ?", s)
+			}
+		}
+		return db.Where("1 = 0")
+	case FilterRedirectChain:
+		switch s {
+		case ChainOnly:
+			return db.Where(chainSQL)
+		case ChainHide:
+			return db.Where("NOT " + chainSQL)
+		}
+		return db.Where("1 = 0")
+	}
+	return db
+}

models/redirect/columns.yaml

@@ -0,0 +1,33 @@
+# Redirects list columns (UI-SPEC C8). match and origin show their labels
+# (the controller's ListExtendRecords) and sort by the stored values.
+columns:
+    source:
+        label: golem15.seo::lang.redirects.source
+        type: text
+        searchable: true
+        sortable: true
+    target:
+        label: golem15.seo::lang.redirects.target
+        type: text
+        searchable: true
+    status:
+        label: golem15.seo::lang.redirects.status
+        type: text
+        sortable: true
+    match:
+        label: golem15.seo::lang.redirects.match
+        type: text
+        sortable: true
+    origin:
+        label: golem15.seo::lang.redirects.origin
+        type: text
+        sortable: true
+    updated_at:
+        label: golem15.seo::lang.redirects.updated
+        type: datetime
+        sortable: true
+    note:
+        label: golem15.seo::lang.redirects.note
+        type: text
+        searchable: true
+        invisible: true

models/redirect/fields.yaml

@@ -0,0 +1,63 @@
+# Redirect form (UI-SPEC C8). The loop refusal and the chain notice land on
+# target; they come from the plugin's own form extension on the redirects
+# controller.
+fields:
+    source:
+        label: golem15.seo::lang.redirects.source
+        comment: golem15.seo::lang.redirects.source_comment
+        type: text
+        span: left
+        required: true
+
+    match:
+        label: golem15.seo::lang.redirects.match
+        type: dropdown
+        span: right
+        default: exact
+        options:
+            exact: golem15.seo::lang.redirects.match_exact
+            pattern: golem15.seo::lang.redirects.match_pattern
+            regex: golem15.seo::lang.redirects.match_regex
+
+    target:
+        label: golem15.seo::lang.redirects.target
+        comment: golem15.seo::lang.redirects.target_comment
+        type: text
+        span: full
+
+    status:
+        label: golem15.seo::lang.redirects.status
+        type: dropdown
+        span: left
+        default: "301"
+        options:
+            "301": golem15.seo::lang.redirects.status_301
+            "302": golem15.seo::lang.redirects.status_302
+            "410": golem15.seo::lang.redirects.status_410
+
+    query:
+        label: golem15.seo::lang.redirects.query
+        type: dropdown
+        span: right
+        default: ignore
+        options:
+            ignore: golem15.seo::lang.redirects.query_ignore
+            pass: golem15.seo::lang.redirects.query_pass
+
+    ignore_case:
+        label: golem15.seo::lang.redirects.ignore_case
+        type: checkbox
+        span: left
+        default: false
+
+    trailing_slash:
+        label: golem15.seo::lang.redirects.trailing_slash
+        type: checkbox
+        span: right
+        default: true
+
+    note:
+        label: golem15.seo::lang.redirects.note
+        type: textarea
+        size: tiny
+        span: full