landed enough rewriters and filters to begin building configurations for the HTML checker

2025-10-29 22:50:25 -06:00
parent e4d7deaf5f
commit eb47b001bb
5 changed files with 614 additions and 19 deletions
@@ -0,0 +1,275 @@
+/*
+ * Amsterdam Web Communities System
+ * Copyright (c) 2025 Erbosoft Metaverse Design Solutions, All Rights Reserved
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+// The database package contains database management and storage logic.
+package database
+
+import (
+	"errors"
+	"math"
+	"strconv"
+	"strings"
+)
+
+// PostLinkData is the structure holding the decoded parts of the post link.
+type PostLinkData struct {
+	Community  string
+	Conference string
+	Topic      int16
+	FirstPost  int32
+	LastPost   int32
+}
+
+// NeedsDBVerification returns true if the post link data needs tro be varified against the database.
+func (d *PostLinkData) NeedsDBVerification() bool {
+	return d.Community != "" || d.Conference != ""
+}
+
+// VerifyNames verifies the post link data against the database.
+func (d *PostLinkData) VerifyNames() error {
+	if d.Community != "" {
+		comm, err := AmGetCommunityByAlias(d.Community)
+		if err != nil {
+			return err
+		}
+		if comm == nil {
+			return errors.New("community alias not found")
+		}
+	}
+	if d.Conference != "" {
+		conf, err := AmGetConferenceByAlias(d.Conference)
+		if err != nil {
+			return err
+		}
+		if conf == nil {
+			return errors.New("conference alias not found")
+		}
+	}
+	return nil
+}
+
+// Maximum lengths of the components.
+const (
+	maxLinkLength       = 130
+	maxCommunityLength  = 32
+	maxConferenceLength = 64
+)
+
+// validateCommunity validates the community name and saves it.
+func validateCommunity(name string, rc *PostLinkData) error {
+	if len(name) > maxCommunityLength {
+		return errors.New("community alias is too long")
+	}
+	if !AmIsValidAmsterdamID(name) {
+		return errors.New("community alias is not a valid identifier")
+	}
+	rc.Community = name
+	return nil
+}
+
+// validateConference validates the conference name and saves it.
+func validateConference(name string, rc *PostLinkData) error {
+	if len(name) > maxConferenceLength {
+		return errors.New("conference alias is too long")
+	}
+	if !AmIsValidAmsterdamID(name) {
+		return errors.New("conference alias is not a valid identifier")
+	}
+	rc.Conference = name
+	return nil
+}
+
+// decodeTopicNumber decodes the topic number and saves it.
+func decodeTopicNumber(data string, rc *PostLinkData) error {
+	v, err := strconv.Atoi(data)
+	if err != nil {
+		return errors.New("invalid topic number reference")
+	}
+	if v > math.MaxInt16 {
+		return errors.New("topic number out of range")
+	}
+	rc.Topic = int16(v)
+	return nil
+}
+
+// decodePostRange decodes the post ranges (first and last post) and saves them.
+func decodePostRange(data string, rc *PostLinkData) error {
+	pos := strings.IndexByte(data, '-')
+	var tempVal int32 = -1
+	if pos > 0 {
+		temp := data[:pos]
+		data = data[pos+1:]
+		v, err := strconv.Atoi(temp)
+		if err != nil {
+			return errors.New("invalid post number reference")
+		}
+		tempVal = int32(v)
+
+		if len(data) == 0 {
+			// range is open-ended (number-)
+			rc.FirstPost = tempVal
+			rc.LastPost = -1
+			return nil
+		}
+	} else if pos == 0 {
+		return errors.New("cannot have - at beginning of post range")
+	}
+
+	v2, err := strconv.Atoi(data)
+	if err != nil {
+		return errors.New("invalid post number reference")
+	}
+	rc.FirstPost = int32(v2)
+	if tempVal >= 0 {
+		if tempVal < rc.FirstPost {
+			// "frontwards" range - reorder the components
+			rc.LastPost = rc.FirstPost
+			rc.FirstPost = tempVal
+		} else {
+			// "backwards" range
+			rc.LastPost = tempVal
+		}
+	} else {
+		// a "range" of a single post
+		rc.LastPost = rc.FirstPost
+	}
+	return nil
+}
+
+/* AmDecodePostLink decodes a post link and returns the complete breakdown of its components.
+ * Parameters:
+ *     data - The post link to be decoded.
+ * Returns:
+ *     Pointer to structure containing post link data, or nil.
+ *     Standard Go error status.
+ */
+func AmDecodePostLink(data string) (*PostLinkData, error) {
+	if data == "" {
+		return nil, errors.New("empty string")
+	}
+	if len(data) > maxLinkLength {
+		return nil, errors.New("post link string too long")
+	}
+	rc := PostLinkData{
+		Community:  "",
+		Conference: "",
+		Topic:      -1,
+		FirstPost:  -1,
+		LastPost:   -1,
+	}
+
+	work := data
+	// First test: Bang
+	pos := strings.IndexByte(work, '!')
+	if pos > 0 {
+		err := validateCommunity(work[:pos], &rc)
+		if err != nil {
+			return nil, err
+		}
+		work = work[pos+1:]
+		if len(work) == 0 {
+			return &rc, nil // community link
+		}
+	} else if pos == 0 {
+		return nil, errors.New("cannot have ! at beginning")
+	}
+
+	// Second test: Dot #1
+	pos = strings.IndexByte(work, '.')
+	if pos < 0 {
+		// no dots in here, must be either "postlink" or "community!conference"
+		var err error
+		if rc.Community == "" {
+			err = decodePostRange(work, &rc)
+		} else {
+			err = validateConference(work, &rc)
+		}
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// Peel off the initial substring before the dot.
+	confOrTopic := work[:pos]
+	work = work[pos+1:]
+	if len(work) == 0 {
+		// we had "conference." or "topic." or maybe "community!conference."
+		if rc.Community == "" {
+			// it's either "conference." or "topic." - try the latter first
+			err := decodeTopicNumber(confOrTopic, &rc)
+			if err != nil {
+				// it's not a topic number, try it as a conference name
+				err = validateConference(confOrTopic, &rc)
+			}
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			// it was "community!conference."
+			err := validateConference(confOrTopic, &rc)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	// Third test: Dot #2
+	pos = strings.IndexByte(work, '.')
+	if pos < 0 {
+		// we had "conference.topic" or "topic.posts" or maybe "community!conference.topic"
+		var err error
+		if rc.Community == "" {
+			// either "conference.topic" or "topic.posts"
+			isTopic := false
+			err = decodeTopicNumber(confOrTopic, &rc)
+			if err != nil {
+				// it's "conference.topic"
+				err = validateConference(confOrTopic, &rc)
+				isTopic = true
+			}
+			if err == nil {
+				if isTopic {
+					err = decodeTopicNumber(work, &rc)
+				} else {
+					err = decodePostRange(work, &rc)
+				}
+			}
+		} else {
+			// we have "community!conference.topic"
+			err = validateConference(confOrTopic, &rc)
+			if err == nil {
+				err = decodeTopicNumber(work, &rc)
+			}
+		}
+		if err != nil {
+			return nil, err
+		}
+		return &rc, nil
+	} else if pos == 0 {
+		return nil, errors.New("cannot have . at beginning of string")
+	}
+
+	// We definitely have "conference.topic.something" or "community!conference.topic.something"
+	err := validateConference(confOrTopic, &rc)
+	if err == nil {
+		err = decodeTopicNumber(work[:pos], &rc)
+	}
+	if err != nil {
+		return nil, err
+	}
+	work = work[pos+1:]
+	if len(work) == 0 {
+		// we had "conference.topic." or "communtiy!conference.topic.", those are both valid
+		return &rc, nil
+	}
+	err = decodePostRange(work, &rc) // the rest must be the post range
+	if err != nil {
+		return nil, err
+	}
+	return &rc, nil
+}