Refactor

8 files changed, 284 insertions, 0 deletions

diff --git a/forged/internal/common/misc/back.go b/forged/internal/common/misc/back.go
new file mode 100644
index 0000000..5351359
--- /dev/null
+++ b/forged/internal/common/misc/back.go
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+package misc
+
+// ErrorBack wraps a value and a channel for communicating an associated error.
+// Typically used to get an error response after sending data across a channel.
+type ErrorBack[T any] struct {
+	Content   T
+	ErrorChan chan error
+}
diff --git a/forged/internal/common/misc/iter.go b/forged/internal/common/misc/iter.go
new file mode 100644
index 0000000..61a96f4
--- /dev/null
+++ b/forged/internal/common/misc/iter.go
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+package misc
+
+import "iter"
+
+// iterSeqLimit returns an iterator equivalent to the supplied one, but stops
+// after n iterations.
+func IterSeqLimit[T any](s iter.Seq[T], n uint) iter.Seq[T] {
+	return func(yield func(T) bool) {
+		var iterations uint
+		for v := range s {
+			if iterations > n-1 {
+				return
+			}
+			if !yield(v) {
+				return
+			}
+			iterations++
+		}
+	}
+}
diff --git a/forged/internal/common/misc/misc.go b/forged/internal/common/misc/misc.go
new file mode 100644
index 0000000..e9e10ab
--- /dev/null
+++ b/forged/internal/common/misc/misc.go
@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+// Package misc provides miscellaneous functions and other definitions.
+package misc
diff --git a/forged/internal/common/misc/net.go b/forged/internal/common/misc/net.go
new file mode 100644
index 0000000..967ea77
--- /dev/null
+++ b/forged/internal/common/misc/net.go
@@ -0,0 +1,42 @@
+package misc
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net"
+	"syscall"
+)
+
+func ListenUnixSocket(ctx context.Context, path string) (listener net.Listener, replaced bool, err error) {
+	listenConfig := net.ListenConfig{} //exhaustruct:ignore
+	listener, err = listenConfig.Listen(ctx, "unix", path)
+	if errors.Is(err, syscall.EADDRINUSE) {
+		replaced = true
+		unlinkErr := syscall.Unlink(path)
+		if unlinkErr != nil {
+			return listener, false, fmt.Errorf("remove existing socket %q: %w", path, unlinkErr)
+		}
+		listener, err = listenConfig.Listen(ctx, "unix", path)
+	}
+	if err != nil {
+		return listener, replaced, fmt.Errorf("listen on unix socket %q: %w", path, err)
+	}
+	return listener, replaced, nil
+}
+
+func Listen(ctx context.Context, net_, addr string) (listener net.Listener, err error) {
+	if net_ == "unix" {
+		listener, _, err = ListenUnixSocket(ctx, addr)
+		if err != nil {
+			return listener, fmt.Errorf("listen unix socket for web: %w", err)
+		}
+	} else {
+		listenConfig := net.ListenConfig{} //exhaustruct:ignore
+		listener, err = listenConfig.Listen(ctx, net_, addr)
+		if err != nil {
+			return listener, fmt.Errorf("listen %s for web: %w", net_, err)
+		}
+	}
+	return listener, nil
+}
diff --git a/forged/internal/common/misc/slices.go b/forged/internal/common/misc/slices.go
new file mode 100644
index 0000000..3ad0211
--- /dev/null
+++ b/forged/internal/common/misc/slices.go
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+package misc
+
+import "strings"
+
+// sliceContainsNewlines returns true if and only if the given slice contains
+// one or more strings that contains newlines.
+func SliceContainsNewlines(s []string) bool {
+	for _, v := range s {
+		if strings.Contains(v, "\n") {
+			return true
+		}
+	}
+	return false
+}
diff --git a/forged/internal/common/misc/trivial.go b/forged/internal/common/misc/trivial.go
new file mode 100644
index 0000000..83901e0
--- /dev/null
+++ b/forged/internal/common/misc/trivial.go
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+package misc
+
+import (
+	"net/url"
+	"strings"
+)
+
+// These are all trivial functions that are intended to be used in HTML
+// templates.
+
+// FirstLine returns the first line of a string.
+func FirstLine(s string) string {
+	before, _, _ := strings.Cut(s, "\n")
+	return before
+}
+
+// PathEscape escapes the input as an URL path segment.
+func PathEscape(s string) string {
+	return url.PathEscape(s)
+}
+
+// QueryEscape escapes the input as an URL query segment.
+func QueryEscape(s string) string {
+	return url.QueryEscape(s)
+}
+
+// Dereference dereferences a pointer.
+func Dereference[T any](p *T) T { //nolint:ireturn
+	return *p
+}
+
+// DereferenceOrZero dereferences a pointer. If the pointer is nil, the zero
+// value of its associated type is returned instead.
+func DereferenceOrZero[T any](p *T) T { //nolint:ireturn
+	if p != nil {
+		return *p
+	}
+	var z T
+	return z
+}
+
+// Minus subtracts two numbers.
+func Minus(a, b int) int {
+	return a - b
+}
diff --git a/forged/internal/common/misc/unsafe.go b/forged/internal/common/misc/unsafe.go
new file mode 100644
index 0000000..d827e7f
--- /dev/null
+++ b/forged/internal/common/misc/unsafe.go
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+package misc
+
+import "unsafe"
+
+// StringToBytes converts a string to a byte slice without copying the string.
+// Memory is borrowed from the string.
+// The resulting byte slice must not be modified in any form.
+func StringToBytes(s string) (bytes []byte) {
+	return unsafe.Slice(unsafe.StringData(s), len(s)) //#nosec G103
+}
+
+// BytesToString converts a byte slice to a string without copying the bytes.
+// Memory is borrowed from the byte slice.
+// The source byte slice must not be modified.
+func BytesToString(b []byte) string {
+	return unsafe.String(unsafe.SliceData(b), len(b)) //#nosec G103
+}
diff --git a/forged/internal/common/misc/url.go b/forged/internal/common/misc/url.go
new file mode 100644
index 0000000..346ff76
--- /dev/null
+++ b/forged/internal/common/misc/url.go
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+package misc
+
+import (
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+// ParseReqURI parses an HTTP request URL, and returns a slice of path segments
+// and the query parameters. It handles %2F correctly.
+func ParseReqURI(requestURI string) (segments []string, params url.Values, err error) {
+	path, paramsStr, _ := strings.Cut(requestURI, "?")
+
+	segments, err = PathToSegments(path)
+	if err != nil {
+		return
+	}
+
+	params, err = url.ParseQuery(paramsStr)
+	return
+}
+
+// PathToSegments splits a path into unescaped segments. It handles %2F correctly.
+func PathToSegments(path string) (segments []string, err error) {
+	segments = strings.Split(strings.TrimPrefix(path, "/"), "/")
+
+	for i, segment := range segments {
+		segments[i], err = url.PathUnescape(segment)
+		if err != nil {
+			return
+		}
+	}
+
+	return
+}
+
+// RedirectDir returns true and redirects the user to a version of the URL with
+// a trailing slash, if and only if the request URL does not already have a
+// trailing slash.
+func RedirectDir(writer http.ResponseWriter, request *http.Request) bool {
+	requestURI := request.RequestURI
+
+	pathEnd := strings.IndexAny(requestURI, "?#")
+	var path, rest string
+	if pathEnd == -1 {
+		path = requestURI
+	} else {
+		path = requestURI[:pathEnd]
+		rest = requestURI[pathEnd:]
+	}
+
+	if !strings.HasSuffix(path, "/") {
+		http.Redirect(writer, request, path+"/"+rest, http.StatusSeeOther)
+		return true
+	}
+	return false
+}
+
+// RedirectNoDir returns true and redirects the user to a version of the URL
+// without a trailing slash, if and only if the request URL has a trailing
+// slash.
+func RedirectNoDir(writer http.ResponseWriter, request *http.Request) bool {
+	requestURI := request.RequestURI
+
+	pathEnd := strings.IndexAny(requestURI, "?#")
+	var path, rest string
+	if pathEnd == -1 {
+		path = requestURI
+	} else {
+		path = requestURI[:pathEnd]
+		rest = requestURI[pathEnd:]
+	}
+
+	if strings.HasSuffix(path, "/") {
+		http.Redirect(writer, request, strings.TrimSuffix(path, "/")+rest, http.StatusSeeOther)
+		return true
+	}
+	return false
+}
+
+// RedirectUnconditionally unconditionally redirects the user back to the
+// current page while preserving query parameters.
+func RedirectUnconditionally(writer http.ResponseWriter, request *http.Request) {
+	requestURI := request.RequestURI
+
+	pathEnd := strings.IndexAny(requestURI, "?#")
+	var path, rest string
+	if pathEnd == -1 {
+		path = requestURI
+	} else {
+		path = requestURI[:pathEnd]
+		rest = requestURI[pathEnd:]
+	}
+
+	http.Redirect(writer, request, path+rest, http.StatusSeeOther)
+}
+
+// SegmentsToURL joins URL segments to the path component of a URL.
+// Each segment is escaped properly first.
+func SegmentsToURL(segments []string) string {
+	for i, segment := range segments {
+		segments[i] = url.PathEscape(segment)
+	}
+	return strings.Join(segments, "/")
+}
+
+// AnyContain returns true if and only if ss contains a string that contains c.
+func AnyContain(ss []string, c string) bool {
+	for _, s := range ss {
+		if strings.Contains(s, c) {
+			return true
+		}
+	}
+	return false
+}