1 files changed, 131 insertions, 0 deletions
diff --git a/src/guff/database-updater.cr b/src/guff/database-updater.cr
new file mode 100644
index 0000000..e06aff3
--- /dev/null
+++ b/src/guff/database-updater.cr
@@ -0,0 +1,131 @@
+require "./database"
+
+module Guff
+  class DatabaseUpdater
+    CURRENT_VERSION = 2_i64
+
+    SQL = {
+      :get_version => "
+        SELECT value
+          FROM metadata
+         WHERE name = 'version'
+      ",
+    }
+
+    MIGRATION_IDS = %w{
+      0-null
+      1-create-tables
+      2-create-indices
+    }
+
+    MIGRATIONS = {
+      "1-create-tables": {
+        backup: false,
+        sql: [%{
+          CREATE TABLE metadata (
+            name    TEXT PRIMARY KEY,
+            value   TEXT NOT NULL 
+          )
+        }, %{
+          INSERT INTO metadata(name, value) VALUES ('version', '1')
+        }, %{
+          CREATE TABLE tags (
+            tag_id      INTEGER PRIMARY KEY,
+            name        TEXT UNIQUE NOT NULL
+          )
+        }, %{
+          CREATE TABLE posts (
+            -- unique id
+            post_id     INTEGER PRIMARY KEY,
+
+            -- false if this post has been deleted
+            is_active   BOOLEAN NOT NULL 
+                        DEFAULT true,
+
+            -- when this post was created
+            created_at  TIMESTAMP WITH TIME ZONE
+                        NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+            -- when this post was posted
+            -- (that is, the draft status was removed)
+            posted_at   TIMESTAMP WITH TIME ZONE
+                        NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+            -- title of post
+            name        TEXT NOT NULL
+                        CHECK (LENGTH(name) > 0)
+
+            -- slug of post (url fragment)
+            slug        TEXT NOT NULL
+                        CHECK (LENGTH(slug) > 0)
+
+            -- body (raw text before filters)
+            body        TEXT NOT NULL
+                        CHECK (LENGTH(body) > 0)
+
+            -- generated html (after filters)
+            html        TEXT NOT NULL
+                        CHECK (LENGTH(html) > 0)
+          )
+        }],
+      },
+
+      "2-create-indices": {
+        backup: false,
+        sql: [%{
+          CREATE INDEX ON tags(name)
+        }, %{
+          CREATE INDEX ON posts(slug)
+        }, %{
+          UPDATE metadata
+             SET value = '2'
+           WHERE name = 'version'
+        }],
+      },
+    } 
+
+    def self.run(path, config)
+      new(path, config).run
+    end
+
+    def initialize(
+      @path   : String,
+      @config : Config
+    )
+      @db = Database.new(path)
+    end
+
+    def run
+      version = 0_i64
+      
+      if @db.table_exists?("metadata")
+        version = @db.one(SQL[:get_version]) as Int64
+      end
+
+      puts "versions: db = %d, code = %d" % [
+        version,
+        CURRENT_VERSION,
+      ]
+
+      if version < CURRENT_VERSION
+        (version + 1).upto(CURRENT_VERSION) do |v|
+          migrate_to(v)
+        end
+      end
+    end
+
+    private def migrate_to(version : Int64)
+      id = MIGRATION_IDS[version]
+      m = MIGRATIONS[id]
+      puts "migrating: %s" % [id]
+
+      (m[:sql] as Array(String)).each do |sql|
+        @db.query(sql)
+      end
+    end
+
+    private def get_version
+      @db.one(:get_version) as Int64
+    end
+  end
+end