add draft for config schema validation

config.lua

@@ -29,10 +29,100 @@ local function findConfigFile()
     return nil
 end
 
+local function insertError(errors, key, message)
+    errors[key] = errors[key] or {}
+    table.insert(errors[key], message)
+    return errors
+end
+
+local function fakeTableSchema(value_schema)
+    return setmetatable({ __list = true }, {
+        __index = function (self, key)
+            return value_schema
+        end
+    })
+end
+
+local SPECIAL_KEYS = {__list = true}
+
+local function validateSchema(schema, input, errors)
+    local errors = errors or {}
+    if schema.__list then
+        -- generate full schema for lists that are same size as input
+        for k, _ in pairs(input) do schema[k] = schema.__schema_value end
+    end
+
+    for key, field_schema in pairs(schema) do
+        if not SPECIAL_KEYS[key] then
+            assert(field_schema, 'schema not provided')
+            local input_value = input[key]
+            local input_type = type(input_value)
+            local wanted_type = field_schema.type
+
+            local actual_wanted_type = wanted_type
+            if wanted_type == 'list' then
+                actual_wanted_type = 'table'
+            end
+
+            if input_type == actual_wanted_type then
+                if wanted_type == 'table' then
+                    -- recursive schema validation for generic tables
+                    errors[key] = errors[key] or {}
+                    validateSchema(field_schema.schema, input_value, errors[key])
+                    if not errors[key] then
+                        errors[key] = nil
+                    end
+                elseif wanted_type == 'list' then
+                    -- for lists (which only have schemas for values), interpret
+                    -- it differently
+                    errors[key] = errors[key] or {}
+                    validateSchema(fakeTableSchema(field_schema.schema), input_value, errors[key])
+                    if next(errors[key]) == nil then
+                        errors[key] = nil
+                    end
+                end
+            else
+                insertError(
+                    errors, key,
+                    string.format('wanted %s but got %s', tostring(wanted_type), tostring(input_type))
+                )
+            end
+        end
+    end
+    return errors
+end
+
+local function validateConfigFile(config_object)
+    local all_schema_errors = {}
+    for module_name, module_config in pairs(config_object.wantedScripts) do
+        local module_manifest = require('scripts.' .. module_name)
+        local config_schema = module_manifest.config
+        local schema_errors = validateSchema(config_schema, module_config)
+        if schema_errors then
+            all_schema_errors[module_name] = schema_errors
+        end
+    end
+    return all_schema_errors
+end
+
+local function writeSchemaErrors(errors, out)
+    out('sex')
+end
+
 local function loadConfigFile()
     local config_file_data = assert(findConfigFile(), 'no config file found, config path: ' .. config_path)
     local config_file_function = assert(loadstring(config_file_data))
-    return config_file_function()
+    local config_object = config_file_function()
+    local schema_errors = validateConfigFile(config_object)
+    if schema_errors then
+        for name, errors in pairs(schema_errors) do
+            log('CONFIG ERROR' .. writeSchemaErrors(errors, log))
+        end
+    end
+    return config_object
 end
 
-return loadConfigFile()
+return {
+    loadConfigFile=loadConfigFile,
+    validateSchema=validateSchema,
+}

main.lua

@@ -7,9 +7,9 @@
 -- local config = loadConfig()
 
 local ctx = require('ctx')
-local conf = require('config')
+local config = require('config')
 
-ctx:loadFromConfig(conf)
+ctx:loadFromConfig(config.loadConfigFile())
 
 return function()
     ctx:onRequest()

scripts/webfinger_allowlist.lua

@@ -37,8 +37,8 @@ return {
     },
     config={
         ['accounts'] = {
-            type='table',
-            value={
+            type='list',
+            schema={
                 type='string',
                 description='ap id'
             },

test.lua

@@ -74,4 +74,5 @@ function onRequest()
 end
 
 require('tests.webfinger_allowlist')
+require('tests.schema_validation')
 os.exit(lu.LuaUnit.run())

tests/schema_validation.lua

@@ -0,0 +1,43 @@
+TestConfigSchemaValidator = {}
+
+local config = require('config')
+
+local function len(t)
+  local count = 0
+  for _ in pairs(t) do count = count + 1 end
+  return count
+end
+
+function pprint(t, ident)
+    local ident = ident or 0
+    if type(t) == 'table' then
+        local count = 0
+        for k, v in pairs(t) do
+            print(string.rep('\t', ident) .. k)
+            pprint(v, ident + 1)
+            count = count + 1
+        end
+        if count == 0 then
+            print('<empty table>')
+        end
+    else
+        print(string.rep('\t', ident) .. tostring(t))
+    end
+end
+
+function TestConfigSchemaValidator:testBasicFields()
+    local errors = config.validateSchema({a={type='string'}}, {a='test'})
+    lu.assertIs(len(errors), 0)
+    local errors = config.validateSchema({a={type='number'}}, {a=123})
+    lu.assertIs(len(errors), 0)
+    local errors = config.validateSchema({a={type='string'}}, {a=123})
+    lu.assertIs(len(errors), 1)
+end
+
+function TestConfigSchemaValidator:testList()
+    local errors = config.validateSchema({a={type='list', schema={type='number'}}}, {a={1,2,3}})
+    lu.assertIs(len(errors), 0)
+
+    local errors = config.validateSchema({a={type='list', schema={type='number'}}}, {a={1,2,3,'asd'}})
+    lu.assertIs(len(errors), 1)
+end