package main

import (
	"errors"
	"fmt"
	"strings"
	"time"

	"git.sr.ht/~emersion/go-scfg"
)

type alertMode int

const (
	single alertMode = iota
	multi
)

type cacheType int

const (
	memory cacheType = iota
	redis
)

type config struct {
	BaseURL     string
	HTTPAddress string
	LogLevel    string
	alertMode   alertMode
	User        string
	Password    string
	ntfy        ntfyConfig
	labels      labels
	cache       cacheConfig
	am          alertmanagerConfig
	resolved    resolvedConfig
}

type ntfyConfig struct {
	Topic       string
	User        string
	Password    string
	AccessToken string
}

type labels struct {
	Order []string
	Label map[string]labelConfig
}

type labelConfig struct {
	Priority string
	Tags     []string
	Icon     string
}

type cacheConfig struct {
	Type            cacheType
	CleanupInterval time.Duration
	Duration        time.Duration
}

type alertmanagerConfig struct {
	User            string
	Password        string
	SilenceDuration time.Duration
	URL             string
}

type resolvedConfig struct {
	Tags []string
	Icon string
}

func readConfig(path string) (*config, error) {
	cfg, err := scfg.Load(path)
	if err != nil {
		return nil, err
	}

	config := new(config)
	// Set default values
	config.HTTPAddress = "127.0.0.1:8080"
	config.LogLevel = "info"
	config.alertMode = single

	config.cache.Type = memory
	config.cache.CleanupInterval = time.Hour
	config.cache.Duration = time.Hour * 24

	d := cfg.Get("log-level")
	if d != nil {
		if err := d.ParseParams(&config.LogLevel); err != nil {
			return nil, err
		}
	}

	d = cfg.Get("http-address")
	if d != nil {
		if err := d.ParseParams(&config.HTTPAddress); err != nil {
			return nil, err
		}
	}

	d = cfg.Get("base-url")
	if d != nil {
		if err := d.ParseParams(&config.BaseURL); err != nil {
			return nil, err
		}
	}

	d = cfg.Get("alert-mode")
	if d != nil {
		var mode string
		if err := d.ParseParams(&mode); err != nil {
			return nil, err
		}

		switch strings.ToLower(mode) {
		case "single":
			config.alertMode = single

		case "multi":
			config.alertMode = multi

		default:
			return nil, fmt.Errorf("%q directive: illegal mode %q", d.Name, mode)
		}
	}

	d = cfg.Get("user")
	if d != nil {
		if err := d.ParseParams(&config.User); err != nil {
			return nil, err
		}
	}

	d = cfg.Get("password")
	if d != nil {
		if err := d.ParseParams(&config.Password); err != nil {
			return nil, err
		}
	}

	if (config.Password != "" && config.User == "") ||
		(config.Password == "" && config.User != "") {
		return nil, errors.New("user and password have to be set together")
	}

	labelsDir := cfg.Get("labels")
	if labelsDir != nil {
		d = labelsDir.Children.Get("order")
		if d != nil {
			var order string
			if err := d.ParseParams(&order); err != nil {
				return nil, err
			}

			config.labels.Order = strings.Split(order, ",")
		}

		labels := make(map[string]labelConfig)
		for _, labelName := range config.labels.Order {
			for _, labelDir := range labelsDir.Children.GetAll(labelName) {
				labelConfig := new(labelConfig)
				var name string

				if err := labelDir.ParseParams(&name); err != nil {
					return nil, err
				}

				d = labelDir.Children.Get("priority")
				if d != nil {
					if err := d.ParseParams(&labelConfig.Priority); err != nil {
						return nil, err
					}
				}

				d = labelDir.Children.Get("tags")
				if d != nil {
					var tags string
					if err := d.ParseParams(&tags); err != nil {
						return nil, err
					}

					labelConfig.Tags = strings.Split(tags, ",")
				}

				d = labelDir.Children.Get("icon")
				if d != nil {
					if err := d.ParseParams(&labelConfig.Icon); err != nil {
						return nil, err
					}
				}

				labels[fmt.Sprintf("%s:%s", labelName, name)] = *labelConfig
			}
		}

		config.labels.Label = labels
	}

	ntfyDir := cfg.Get("ntfy")
	if ntfyDir == nil {
		return nil, fmt.Errorf("%q directive missing", "ntfy")
	}

	d = ntfyDir.Children.Get("topic")
	if d == nil {
		return nil, fmt.Errorf("%q missing from %q directive", "topic", "ntfy")
	}
	if err := d.ParseParams(&config.ntfy.Topic); err != nil {
		return nil, err
	}

	d = ntfyDir.Children.Get("user")
	if d != nil {
		if err := d.ParseParams(&config.ntfy.User); err != nil {
			return nil, err
		}
	}

	d = ntfyDir.Children.Get("password")
	if d != nil {
		if err := d.ParseParams(&config.ntfy.Password); err != nil {
			return nil, err
		}
	}

	if (config.ntfy.Password != "" && config.ntfy.User == "") ||
		(config.ntfy.Password == "" && config.ntfy.User != "") {
		return nil, errors.New("ntfy: user and password have to be set together")
	}

	d = ntfyDir.Children.Get("access-token")
	if d != nil {
		if err := d.ParseParams(&config.ntfy.AccessToken); err != nil {
			return nil, err
		}
	}

	if config.ntfy.User != "" && config.ntfy.AccessToken != "" {
		return nil, errors.New("ntfy: cannot use both an access-token and a user/password at the same time")
	}

	cacheDir := cfg.Get("cache")

	if cacheDir != nil {
		d = cacheDir.Children.Get("type")
		if d != nil {
			var cacheType string
			if err := d.ParseParams(&cacheType); err != nil {
				return nil, err
			}

			switch strings.ToLower(cacheType) {
			case "memory":
				config.cache.Type = memory
			case "redis":
				config.cache.Type = redis
			default:
				return nil, fmt.Errorf("cache: illegal type %q", cacheType)
			}
		}

		var durationString string
		d = cacheDir.Children.Get("duration")
		if d != nil {
			if err := d.ParseParams(&durationString); err != nil {
				return nil, err
			}

			duration, err := time.ParseDuration(durationString)
			if err != nil {
				return nil, err
			}

			config.cache.Duration = duration
		}

		var cleanupIntervalString string
		d = cacheDir.Children.Get("cleanup-interval")
		if d != nil {
			if err := d.ParseParams(&cleanupIntervalString); err != nil {
				return nil, err
			}

			interval, err := time.ParseDuration(cleanupIntervalString)
			if err != nil {
				return nil, err
			}

			config.cache.CleanupInterval = interval
		}
	}

	amDir := cfg.Get("alertmanager")

	if amDir != nil {
		var durationString string
		d = amDir.Children.Get("silence-duration")
		if d != nil {
			if err := d.ParseParams(&durationString); err != nil {
				return nil, err
			}

			duration, err := time.ParseDuration(durationString)
			if err != nil {
				return nil, err
			}

			config.am.SilenceDuration = duration
		}

		d = amDir.Children.Get("user")
		if d != nil {
			if err := d.ParseParams(&config.am.User); err != nil {
				return nil, err
			}
		}

		d = amDir.Children.Get("password")
		if d != nil {
			if err := d.ParseParams(&config.am.Password); err != nil {
				return nil, err
			}
		}

		if (config.am.Password != "" && config.am.User == "") ||
			(config.am.Password == "" && config.am.User != "") {
			return nil, errors.New("alertmanager: user and password have to be set together")
		}

		d = amDir.Children.Get("url")
		if d != nil {
			if err := d.ParseParams(&config.am.URL); err != nil {
				return nil, err
			}
		}
	}

	resolvedDir := cfg.Get("resolved")
	if resolvedDir != nil {
		d = resolvedDir.Children.Get("tags")
		if d != nil {
			var tags string
			if err := d.ParseParams(&tags); err != nil {
				return nil, err
			}

			config.resolved.Tags = strings.Split(tags, ",")
		}

		d = resolvedDir.Children.Get("icon")
		if d != nil {
			if err := d.ParseParams(&config.resolved.Icon); err != nil {
				return nil, err
			}
		}
	}

	return config, nil
}