From 5b7d710f5a11707b7c76c04790d0304d6affee8b Mon Sep 17 00:00:00 2001
From: Fuwn <contact@fuwn.me>
Date: Thu, 22 Jan 2026 00:04:37 -0800
Subject: feat: Add config imports for monitor inheritance

---
 internal/config/config.go | 86 +++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 84 insertions(+), 2 deletions(-)

diff --git a/internal/config/config.go b/internal/config/config.go
index 7542d3e..f97add5 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net/url"
 	"os"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -12,6 +13,7 @@ import (
 
 // Config represents the root configuration structure
 type Config struct {
+	Imports   []string         `yaml:"imports,omitempty"`
 	Site      SiteConfig       `yaml:"site"`
 	Server    ServerConfig     `yaml:"server"`
 	Storage   StorageConfig    `yaml:"storage"`
@@ -238,6 +240,21 @@ func (d Duration) MarshalYAML() (interface{}, error) {
 
 // Load reads and parses a configuration file
 func Load(path string) (*Config, error) {
+	visited := make(map[string]bool)
+	return loadWithImports(path, visited)
+}
+
+func loadWithImports(path string, visited map[string]bool) (*Config, error) {
+	absPath, err := filepath.Abs(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve path %q: %w", path, err)
+	}
+
+	if visited[absPath] {
+		return nil, fmt.Errorf("circular import detected: %q", path)
+	}
+	visited[absPath] = true
+
 	data, err := os.ReadFile(path)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read config file: %w", err)
@@ -248,10 +265,15 @@ func Load(path string) (*Config, error) {
 		return nil, fmt.Errorf("failed to parse config file: %w", err)
 	}
 
-	// Apply defaults
+	if len(cfg.Imports) > 0 {
+		baseDir := filepath.Dir(absPath)
+		if err := cfg.processImports(baseDir, visited); err != nil {
+			return nil, err
+		}
+	}
+
 	cfg.applyDefaults()
 
-	// Validate configuration
 	if err := cfg.validate(); err != nil {
 		return nil, fmt.Errorf("invalid configuration: %w", err)
 	}
@@ -259,6 +281,66 @@ func Load(path string) (*Config, error) {
 	return &cfg, nil
 }
 
+func (c *Config) processImports(baseDir string, visited map[string]bool) error {
+	for _, importPath := range c.Imports {
+		fullPath := importPath
+		if !filepath.IsAbs(importPath) {
+			fullPath = filepath.Join(baseDir, importPath)
+		}
+
+		imported, err := loadWithImports(fullPath, visited)
+		if err != nil {
+			return fmt.Errorf("failed to import %q: %w", importPath, err)
+		}
+
+		c.mergeImported(imported)
+	}
+	return nil
+}
+
+func (c *Config) mergeImported(imported *Config) {
+	groupIndex := make(map[string]int)
+	for i, g := range c.Groups {
+		groupIndex[g.Name] = i
+	}
+
+	for _, importedGroup := range imported.Groups {
+		if idx, exists := groupIndex[importedGroup.Name]; exists {
+			c.Groups[idx] = mergeGroups(c.Groups[idx], importedGroup)
+		} else {
+			c.Groups = append(c.Groups, importedGroup)
+			groupIndex[importedGroup.Name] = len(c.Groups) - 1
+		}
+	}
+
+	incidentSet := make(map[string]bool)
+	for _, inc := range c.Incidents {
+		incidentSet[inc.Title] = true
+	}
+	for _, inc := range imported.Incidents {
+		if !incidentSet[inc.Title] {
+			c.Incidents = append(c.Incidents, inc)
+			incidentSet[inc.Title] = true
+		}
+	}
+}
+
+func mergeGroups(local, imported GroupConfig) GroupConfig {
+	monitorIndex := make(map[string]int)
+	for i, m := range local.Monitors {
+		monitorIndex[m.Name] = i
+	}
+
+	for _, importedMon := range imported.Monitors {
+		if _, exists := monitorIndex[importedMon.Name]; !exists {
+			local.Monitors = append(local.Monitors, importedMon)
+			monitorIndex[importedMon.Name] = len(local.Monitors) - 1
+		}
+	}
+
+	return local
+}
+
 // applyDefaults sets default values for missing configuration
 func (c *Config) applyDefaults() {
 	if c.Site.Name == "" {
-- 
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