// conditions_codes.go selects current-conditions WMO codes from source candidates.
// Layer: adapters/outbound/postgres conditions feature.
package postgres

import "gitea.maximumdirect.net/ejr/weatherfeeder/model"

type currentConditionsConditionCodeCandidate struct {
	EventSource   string
	ConditionCode model.WMOCode
}

type conditionCodeFamily int

const (
	conditionCodeFamilyUnknown conditionCodeFamily = iota
	conditionCodeFamilyClearOrCloud
	conditionCodeFamilyFog
	conditionCodeFamilyDrizzle
	conditionCodeFamilyRain
	conditionCodeFamilySnow
	conditionCodeFamilyThunderstorm
)

var currentConditionsConditionCodeRankings = map[conditionCodeFamily][]model.WMOCode{
	conditionCodeFamilyClearOrCloud: {0, 1, 2, 3},
	conditionCodeFamilyFog:          {45, 48},
	conditionCodeFamilyDrizzle:      {51, 53, 55, 56, 57},
	conditionCodeFamilyRain:         {61, 63, 65, 80, 81, 82, 66, 67},
	conditionCodeFamilySnow:         {71, 73, 75, 85, 86, 77},
	conditionCodeFamilyThunderstorm: {95, 96, 99},
}

var currentConditionsConditionCodeFamilies = buildCurrentConditionsConditionCodeFamilies()

func buildCurrentConditionsConditionCodeFamilies() map[model.WMOCode]conditionCodeFamily {
	families := make(map[model.WMOCode]conditionCodeFamily)
	for family, ranking := range currentConditionsConditionCodeRankings {
		for _, code := range ranking {
			families[code] = family
		}
	}
	return families
}

func selectCurrentConditionsConditionCode(candidates []currentConditionsConditionCodeCandidate) model.WMOCode {
	seenSources := make(map[string]struct{})
	familyCounts := make(map[conditionCodeFamily]int)
	codeCounts := make(map[model.WMOCode]int)

	for _, candidate := range candidates {
		if _, seen := seenSources[candidate.EventSource]; seen {
			continue
		}
		seenSources[candidate.EventSource] = struct{}{}

		family, ok := currentConditionsConditionCodeFamilies[candidate.ConditionCode]
		if !ok {
			continue
		}
		familyCounts[family]++
		codeCounts[candidate.ConditionCode]++
	}

	winningFamily, ok := currentConditionsWinningConditionCodeFamily(familyCounts)
	if !ok {
		return model.WMOUnknown
	}

	return currentConditionsWinningConditionCode(winningFamily, codeCounts)
}

func currentConditionsWinningConditionCodeFamily(counts map[conditionCodeFamily]int) (conditionCodeFamily, bool) {
	winningFamily := conditionCodeFamilyUnknown
	winningCount := 0
	tied := false

	for family, count := range counts {
		if count > winningCount {
			winningFamily = family
			winningCount = count
			tied = false
			continue
		}
		if count == winningCount {
			tied = true
		}
	}

	if winningCount == 0 || tied {
		return conditionCodeFamilyUnknown, false
	}
	return winningFamily, true
}

func currentConditionsWinningConditionCode(family conditionCodeFamily, counts map[model.WMOCode]int) model.WMOCode {
	winningCode := model.WMOUnknown
	winningCount := 0

	for _, code := range currentConditionsConditionCodeRankings[family] {
		if counts[code] > winningCount {
			winningCode = code
			winningCount = counts[code]
		}
	}

	return winningCode
}