Initial MVP commit

internal/platform/config/config.go

@@ -0,0 +1,120 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+// Config holds weatherapi datasource configuration.
+type Config struct {
+	Databases []DatabaseConfig
+}
+
+type DatabaseConfig struct {
+	Name   string         `yaml:"name"`
+	Driver string         `yaml:"driver"`
+	Params DatabaseParams `yaml:"params"`
+}
+
+type DatabaseParams struct {
+	URI      string `yaml:"uri"`
+	Username string `yaml:"username"`
+	Password string `yaml:"password"`
+}
+
+type configWrapper struct {
+	Databases []DatabaseConfig `yaml:"databases"`
+}
+
+func Load(path string) (*Config, error) {
+	if strings.TrimSpace(path) == "" {
+		path = "config.yml"
+	}
+
+	raw, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("config.Load: read %q: %w", path, err)
+	}
+
+	var list []DatabaseConfig
+	if err := decodeStrict(raw, &list); err == nil && len(list) > 0 {
+		cfg := &Config{Databases: list}
+		if err := cfg.Validate(); err != nil {
+			return nil, err
+		}
+		return cfg, nil
+	}
+
+	var wrapped configWrapper
+	if err := decodeStrict(raw, &wrapped); err != nil {
+		return nil, fmt.Errorf("config.Load: parse YAML %q: %w", path, err)
+	}
+
+	cfg := &Config{Databases: wrapped.Databases}
+	if err := cfg.Validate(); err != nil {
+		return nil, err
+	}
+
+	return cfg, nil
+}
+
+func decodeStrict(raw []byte, out any) error {
+	dec := yaml.NewDecoder(strings.NewReader(string(raw)))
+	dec.KnownFields(true)
+	if err := dec.Decode(out); err != nil {
+		return err
+	}
+
+	var extra any
+	if err := dec.Decode(&extra); err == nil {
+		return fmt.Errorf("contains multiple YAML documents; expected exactly one")
+	}
+	return nil
+}
+
+func (c *Config) Validate() error {
+	if c == nil {
+		return fmt.Errorf("config validation failed: config is nil")
+	}
+	if len(c.Databases) == 0 {
+		return fmt.Errorf("config validation failed: no databases configured")
+	}
+
+	seen := map[string]struct{}{}
+	for i, db := range c.Databases {
+		path := fmt.Sprintf("databases[%d]", i)
+		if strings.TrimSpace(db.Name) == "" {
+			return fmt.Errorf("config validation failed: %s.name is required", path)
+		}
+		if _, ok := seen[db.Name]; ok {
+			return fmt.Errorf("config validation failed: %s.name %q is duplicated", path, db.Name)
+		}
+		seen[db.Name] = struct{}{}
+
+		if strings.TrimSpace(db.Driver) == "" {
+			return fmt.Errorf("config validation failed: %s.driver is required", path)
+		}
+		if strings.TrimSpace(db.Params.URI) == "" {
+			return fmt.Errorf("config validation failed: %s.params.uri is required", path)
+		}
+		if strings.TrimSpace(db.Params.Username) == "" {
+			return fmt.Errorf("config validation failed: %s.params.username is required", path)
+		}
+		if strings.TrimSpace(db.Params.Password) == "" {
+			return fmt.Errorf("config validation failed: %s.params.password is required", path)
+		}
+	}
+	return nil
+}
+
+func (c *Config) FindDatabase(name string) (DatabaseConfig, bool) {
+	for _, db := range c.Databases {
+		if db.Name == name {
+			return db, true
+		}
+	}
+	return DatabaseConfig{}, false
+}

internal/platform/config/config_test.go

@@ -0,0 +1,53 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLoadRootList(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "config.yml")
+	content := `
+- name: weatherdb
+  driver: postgres
+  params:
+    uri: postgres://weatherdb:5432/weatherdb?sslmode=disable
+    username: weatherdb
+    password: weatherdb
+`
+	if err := os.WriteFile(path, []byte(content), 0o600); err != nil {
+		t.Fatalf("write temp config: %v", err)
+	}
+
+	cfg, err := Load(path)
+	if err != nil {
+		t.Fatalf("load config: %v", err)
+	}
+	if len(cfg.Databases) != 1 {
+		t.Fatalf("expected one database, got %d", len(cfg.Databases))
+	}
+	if cfg.Databases[0].Name != "weatherdb" {
+		t.Fatalf("unexpected db name %q", cfg.Databases[0].Name)
+	}
+}
+
+func TestLoadMissingRequiredFieldFails(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "config.yml")
+	content := `
+- name: weatherdb
+  driver: postgres
+  params:
+    username: weatherdb
+    password: weatherdb
+`
+	if err := os.WriteFile(path, []byte(content), 0o600); err != nil {
+		t.Fatalf("write temp config: %v", err)
+	}
+
+	if _, err := Load(path); err == nil {
+		t.Fatalf("expected validation error for missing params.uri")
+	}
+}