feat: Use composite group/name key for monitor identification

Previously monitors were identified by just their name, causing monitors
with the same name in different groups to share data in the database.

Changes:
- Add ID() method to MonitorConfig returning 'group/name' format
- Add Group field to MonitorConfig (set at runtime)
- Update Monitor interface with ID() and Group() methods
- Update all monitor implementations (http, tcp, dns, icmp, gemini,
  graphql, database) to use composite ID
- Update Scheduler to use monitor ID instead of name
- Update server handlers to use composite ID for stats lookups
- Change API routes to use {group}/{name} pattern:
  - /api/monitor/{group}/{name}
  - /api/history/{group}/{name}
  - /api/uptime/{group}/{name}
  - /api/badge/{group}/{name}.svg
- URL-encode group and name components to handle special characters
  (e.g., slashes in names become %2F)
- Update config.UpdateResetFlag to accept group and name separately

BREAKING: API endpoints now require group in the path. Existing database
data using just monitor names won't be associated with the new composite
keys.

1 files changed, 67 insertions, 4 deletions

diff --git a/internal/config/config.go b/internal/config/config.go
index 0c8b430..7542d3e 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -2,6 +2,7 @@ package config
 
 import (
 	"fmt"
+	"net/url"
 	"os"
 	"strings"
 	"time"
@@ -117,6 +118,7 @@ type MonitorDefaults struct {
 // MonitorConfig represents a single monitor
 type MonitorConfig struct {
 	Name                 string            `yaml:"name"`
+	Group                string            `yaml:"-"`    // Set at runtime, not from YAML - the group this monitor belongs to
 	Type                 string            `yaml:"type"` // http, https, tcp, gemini
 	Target               string            `yaml:"target"`
 	Link                 string            `yaml:"link,omitempty"` // Custom URL for clicking the monitor name (e.g., docs page)
@@ -151,6 +153,45 @@ type MonitorConfig struct {
 	DBType string `yaml:"db_type,omitempty"` // Database type: postgres, mysql, redis, memcached, mongodb
 }
 
+// ID returns the unique identifier for this monitor (group/name format)
+// Both group and name are URL-encoded to handle special characters like '/'
+func (m *MonitorConfig) ID() string {
+	if m.Group == "" {
+		return url.PathEscape(m.Name)
+	}
+	return url.PathEscape(m.Group) + "/" + url.PathEscape(m.Name)
+}
+
+// ParseMonitorID splits a monitor ID back into group and name components
+// Returns (group, name, ok) where ok is false if the ID format is invalid
+func ParseMonitorID(id string) (group, name string, ok bool) {
+	// Find the separator (first unescaped '/')
+	idx := strings.Index(id, "/")
+	if idx == -1 {
+		// No group, just a name
+		decoded, err := url.PathUnescape(id)
+		if err != nil {
+			return "", "", false
+		}
+		return "", decoded, true
+	}
+
+	groupPart := id[:idx]
+	namePart := id[idx+1:]
+
+	decodedGroup, err := url.PathUnescape(groupPart)
+	if err != nil {
+		return "", "", false
+	}
+
+	decodedName, err := url.PathUnescape(namePart)
+	if err != nil {
+		return "", "", false
+	}
+
+	return decodedGroup, decodedName, true
+}
+
 // IncidentConfig represents an incident or maintenance
 type IncidentConfig struct {
 	Title            string           `yaml:"title"`
@@ -285,6 +326,9 @@ func (c *Config) applyDefaults() {
 		for j := range c.Groups[i].Monitors {
 			m := &c.Groups[i].Monitors[j]
 
+			// Set the group name on the monitor
+			m.Group = grp.Name
+
 			// Apply group-level defaults first, then monitor-level overrides
 			if m.Interval.Duration == 0 {
 				if grp.Defaults != nil && grp.Defaults.Interval != nil {
@@ -534,7 +578,8 @@ type MonitorWithGroup struct {
 
 // UpdateResetFlag updates the reset_on_next_check flag for a specific monitor in the config file
 // Uses a line-based approach to preserve original formatting and omitted fields
-func UpdateResetFlag(configPath string, monitorName string, value bool) error {
+// groupName and monitorName are used to find the correct monitor in the YAML structure
+func UpdateResetFlag(configPath string, groupName string, monitorName string, value bool) error {
 	// Read the config file
 	data, err := os.ReadFile(configPath)
 	if err != nil {
@@ -542,6 +587,7 @@ func UpdateResetFlag(configPath string, monitorName string, value bool) error {
 	}
 
 	lines := strings.Split(string(data), "\n")
+	inTargetGroup := false
 	inMonitor := false
 	monitorIndent := ""
 	foundMonitor := false
@@ -550,8 +596,25 @@ func UpdateResetFlag(configPath string, monitorName string, value bool) error {
 		line := lines[i]
 		trimmed := strings.TrimSpace(line)
 
-		// Check if this is the start of our target monitor
-		if strings.HasPrefix(trimmed, "- name:") || strings.HasPrefix(trimmed, "name:") {
+		// Check if this is a group name line
+		if strings.HasPrefix(trimmed, "- name:") && !inMonitor {
+			// Could be a group name - check if it matches our target group
+			namePart := strings.TrimPrefix(trimmed, "- name:")
+			namePart = strings.TrimSpace(namePart)
+			namePart = strings.Trim(namePart, "\"'")
+
+			// Check if this is our target group
+			if namePart == groupName {
+				inTargetGroup = true
+			} else if inTargetGroup {
+				// We've moved to a different group, stop looking
+				break
+			}
+			continue
+		}
+
+		// Check if this is the start of our target monitor (within the target group)
+		if inTargetGroup && (strings.HasPrefix(trimmed, "- name:") || strings.HasPrefix(trimmed, "name:")) {
 			// Extract monitor name from line
 			namePart := strings.TrimPrefix(trimmed, "- name:")
 			namePart = strings.TrimPrefix(namePart, "name:")
@@ -597,7 +660,7 @@ func UpdateResetFlag(configPath string, monitorName string, value bool) error {
 	}
 
 	if !foundMonitor {
-		return fmt.Errorf("monitor %q not found in config", monitorName)
+		return fmt.Errorf("monitor %q in group %q not found in config", monitorName, groupName)
 	}
 
 	// Write back to file