3 files changed, 129 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
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--- /dev/null
+++ b/.gitignore
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+build/
diff --git a/project.janet b/project.janet
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+++ b/project.janet
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+(declare-project
+  :name "webgen"
+  :description "Static web generator"
+  :dependencies ["https://github.com/janet-lang/path.git"
+                 "https://github.com/jeannekamikaze/janet-filesystem.git"])
+
+(declare-executable
+  :name "webgen"
+  :entry "webgen.janet")
diff --git a/webgen.janet b/webgen.janet
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+++ b/webgen.janet
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+(import filesystem)
+(import path)
+
+(defn pairs->table
+  "Convert an array of pairs into a table."
+  [pairs]
+  (reduce (fn [acc [key val]] (put acc key val)) @{} pairs))
+
+(defn split-first
+  "Split the string on the first occurrence of the delimeter. If the delimeter
+  is not found, return the original string."
+  [delim str]
+  (def idx (string/find delim str))
+  (if idx
+    @[(string/slice str 0 (- idx 1)) (string/slice str (+ idx 1))]
+    str))
+
+(defn nesting-levels
+  "Return the number of nesting levels in the given file path."
+  [path]
+  (length (string/find-all path/sep path)))
+
+(defn markdown-file-to-html
+  "Read and convert a markdown file to html. Return an html buffer."
+  [path]
+  (def quoted-path (string "\"" path "\""))
+  (with [stdout (file/popen (string "pandoc -f markdown --mathjax " quoted-path) :r)]
+    (file/read stdout :all)))
+
+(defn substitute-variables
+  "Perform variable substitution on the given string."
+  [variables path str]
+  (var str str)
+  (def max-recursion-depth 5)
+  (loop [i :in (range max-recursion-depth)]
+    (loop [[variable body] :pairs variables]
+      (def variable-str (string "${" variable "}"))
+      (set str (string/replace variable-str body str))))
+  (string/replace-all "${ROOT}/" (string/repeat "../" (- (nesting-levels path) 1)) str))
+
+(defn process-html
+  "Process the given HTML contents, applying the website's template and
+  applying variable substitution."
+  [template variables path contents]
+  (substitute-variables variables path
+    (string/replace "${CONTENTS}" contents
+      template)))
+
+(defn process-markdown-file
+  "Process a markdown file. Return the resulting HTML."
+  [process-html path]
+  (process-html path (markdown-file-to-html path)))
+
+(defn process-file
+  "Process a file with the given contents processor. The process takes a file
+  path and the file's contents."
+  [process path]
+    (process path (filesystem/read-file path)))
+
+(defn process-files
+  "Process the files in the source directory and write the results to the
+  destination directory."
+  [process source-dir dest-dir]
+  (each file (filesystem/list-all-files source-dir)
+    (process file)))
+
+(defn make-processor
+  "Create a function that processes files based on their extension."
+  [src-dir build-dir template variables]
+  (fn [src-filepath]
+    (print "Processing file " src-filepath)
+    (def ext (path/ext src-filepath))
+    (def processed-contents
+      (match ext
+        ".css"       (process-file (partial substitute-variables variables) src-filepath)
+        ".html"      (process-file (partial process-html template variables) src-filepath)
+        ".md"        (process-markdown-file (partial process-html template variables) src-filepath)
+        ".markdown"  (process-markdown-file (partial process-html template variables) src-filepath)
+        _ nil)) # nil means we copy the file as is.
+    (var dst-filepath (string/replace src-dir build-dir src-filepath))
+    (set dst-filepath
+      (match ext
+        ".md" (string/replace ext ".html" dst-filepath)
+        ".markdown" (string/replace ext ".html" dst-filepath)
+        _ dst-filepath))
+    (if processed-contents
+      (filesystem/write-file dst-filepath processed-contents)
+      (filesystem/copy-file src-filepath dst-filepath))))
+
+(defn read-map-file
+  "Read key-value pairs from a file. The file should be a text file with lines
+  of the form |key = value|. Return a table."
+  [path]
+  (def contents (filesystem/read-file path))
+  (def lines (filter (fn [x] (not (empty? x))) (string/split "\n" contents)))
+  (def name-body-pairs (map (fn [line]
+    (def @[name body] (split-first "=" line))
+      @[(string/trim name) (string/trim body)])
+    lines))
+  (pairs->table name-body-pairs))
+
+(defn usage [argv0]
+  (print "Usage: " argv0 " <source dir>")
+  (os/exit 0))
+
+(defn main [argv0 &opt src-dir]
+  (when (nil? src-dir) (usage argv0))
+  (def src-dir (path/normalize src-dir))
+  (def config (read-map-file (path/join src-dir "config.txt")))
+  (def build-dir (path/normalize (string (get config "BUILD-DIR") path/sep)))
+  (print "Generating website: " src-dir " -> " build-dir)
+  (def template-file (get config "TEMPLATE-FILE"))
+  (def variables-file (get config "VARIABLES-FILE"))
+  (def template (filesystem/read-file (path/join src-dir template-file)))
+  (def variables (read-map-file (path/join src-dir variables-file)))
+  (def processor (make-processor src-dir build-dir template variables))
+  # For clean builds, re-create the build directory.
+  (filesystem/recreate-directory build-dir)
+  (process-files processor src-dir build-dir))