From ac1391e64a8fdcb453560fa887ea54541cebec5e Mon Sep 17 00:00:00 2001
From: Timur Ismagilov <bouncepaw2@ya.ru>
Date: Sun, 22 May 2022 12:25:22 +0300
Subject: [PATCH] Interwiki: Start implementing

---
 files/files.go         |  4 ++++
 interwiki/interwiki.go | 49 ++++++++++++++++++++++++++++++++++++++++++
 interwiki/map.go       | 14 ++++++++++++
 interwiki/wiki.go      | 43 ++++++++++++++++++++++++++++++++++++
 main.go                |  1 +
 5 files changed, 111 insertions(+)
 create mode 100644 interwiki/interwiki.go
 create mode 100644 interwiki/map.go
 create mode 100644 interwiki/wiki.go

diff --git a/files/files.go b/files/files.go
index f957fb6..32824a5 100644
--- a/files/files.go
+++ b/files/files.go
@@ -16,6 +16,7 @@ var paths struct {
 	tokensJSON          string
 	userCredentialsJSON string
 	categoriesJSON      string
+	interwikiJSON       string
 }
 
 // HyphaeDir returns the path to hyphae storage.
@@ -45,6 +46,8 @@ func CategoriesJSON() string { return paths.categoriesJSON }
 // FileInRoot returns full path for the given filename if it was placed in the root of the wiki structure.
 func FileInRoot(filename string) string { return filepath.Join(cfg.WikiDir, filename) }
 
+func InterwikiJSON() string { return paths.interwikiJSON }
+
 // PrepareWikiRoot ensures all needed directories and files exist and have
 // correct permissions.
 func PrepareWikiRoot() error {
@@ -72,6 +75,7 @@ func PrepareWikiRoot() error {
 
 	paths.tokensJSON = filepath.Join(paths.cacheDir, "tokens.json")
 	paths.categoriesJSON = filepath.Join(cfg.WikiDir, "categories.json")
+	paths.interwikiJSON = FileInRoot("interwiki.json")
 
 	return nil
 }
diff --git a/interwiki/interwiki.go b/interwiki/interwiki.go
new file mode 100644
index 0000000..05ade08
--- /dev/null
+++ b/interwiki/interwiki.go
@@ -0,0 +1,49 @@
+// Package interwiki provides interwiki capabilities. Most of them, at least.
+package interwiki
+
+import (
+	"encoding/json"
+	"github.com/bouncepaw/mycorrhiza/files"
+	"log"
+	"os"
+)
+
+func Init() {
+	var (
+		record, err = readInterwiki()
+	)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	for _, wiki := range record {
+		wiki.canonize()
+		theMap.list = append(theMap.list, &wiki)
+		for _, prefix := range wiki.Names {
+			if _, found := theMap.byName[prefix]; found {
+				log.Fatalf("There are multiple interwiki map entries having the same prefix ‘%s’\n", prefix)
+			} else {
+				theMap.byName[prefix] = &wiki
+			}
+		}
+	}
+	log.Printf("Loaded %d interwiki entries\n", len(theMap.list))
+}
+
+func readInterwiki() ([]Wiki, error) {
+	var (
+		record            []Wiki
+		fileContents, err = os.ReadFile(files.InterwikiJSON())
+	)
+	if os.IsNotExist(err) {
+		return record, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	err = json.Unmarshal(fileContents, &record)
+	if err != nil {
+		return nil, err
+	}
+	return record, nil
+}
diff --git a/interwiki/map.go b/interwiki/map.go
new file mode 100644
index 0000000..989788a
--- /dev/null
+++ b/interwiki/map.go
@@ -0,0 +1,14 @@
+package interwiki
+
+// Map is an interwiki map
+type Map struct {
+	list   []*Wiki
+	byName map[string]*Wiki
+}
+
+var theMap Map
+
+func init() {
+	theMap.list = []*Wiki{}
+	theMap.byName = map[string]*Wiki{}
+}
diff --git a/interwiki/wiki.go b/interwiki/wiki.go
new file mode 100644
index 0000000..49504f7
--- /dev/null
+++ b/interwiki/wiki.go
@@ -0,0 +1,43 @@
+package interwiki
+
+// WikiEngine is an enumeration of supported interwiki targets.
+type WikiEngine int
+
+const (
+	// Mycorrhiza is a Mycorrhiza wiki. This is the default value.
+	Mycorrhiza WikiEngine = iota
+	// Generic is any website.
+	Generic
+)
+
+// Wiki is an entry in the interwiki map.
+type Wiki struct {
+	// Names is a slice of link prefices that correspond to this wiki.
+	Names []string `json:"names"`
+
+	// URL is the address of the wiki.
+	URL string `json:"url"`
+
+	// LinkFormat is a format string for incoming interwiki links. The format strings should look like this:
+	//     http://wiki.example.org/view/%s
+	// where %s is where text will be inserted. No other % instructions are supported yet. They will be added once we learn of their use cases.
+	//
+	// This field is optional. For Generic wikis, it is automatically set to <URL>/%s; for Mycorrhiza wikis, it is automatically set to <URL>/hypha/%s.
+	LinkFormat string `json:"link_format"`
+
+	// Description is a plain-text description of the wiki.
+	Description string `json:"description"`
+
+	// Engine is the engine of the wiki. This field is not set in JSON.
+	Engine WikiEngine `json:"-"`
+
+	// EngineString is a string name of the engine. It is then converted to Engine. Supported values are:
+	//     * mycorrhiza -> Mycorrhiza
+	//     * generic -> Generic
+	// All other values will result in an error.
+	EngineString string `json:"engine"`
+}
+
+func (w *Wiki) canonize() {
+
+}
diff --git a/main.go b/main.go
index 72d9a41..ad09d2a 100644
--- a/main.go
+++ b/main.go
@@ -51,6 +51,7 @@ func main() {
 	migration.MigrateHeadingsMaybe()
 	shroom.SetHeaderLinks()
 	categories.Init()
+	// interwiki.Init()
 
 	// Static files:
 	static.InitFS(files.StaticFiles())