package topdata

import (
	"fmt"
	"path/filepath"
	"slices"
	"strings"
)

// validateClassFeatMasterfeatAccessibility warns when a class feat table
// references a masterfeat whose member feats are silently dropped from
// expansion by classFeatExpansionCanUseFeat. Only the ambiguous case is
// flagged: ALLCLASSESCANUSE=0 with no MinLevelClass, where the feat cannot
// be obtained by any class at all. Exclusions with an explicit MinLevelClass
// are deliberate cross-class restrictions and stay silent.
func validateClassFeatMasterfeatAccessibility(dataDir string, report *ValidationReport) {
	datasets, err := discoverNativeDatasets(dataDir)
	if err != nil {
		return
	}
	keyToID := map[string]int{}
	var featRowByKey map[string]map[string]any
	type classFeatTable struct {
		path     string
		classKey string
		rows     []map[string]any
	}
	classTables := []classFeatTable{}
	for _, dataset := range datasets {
		name := filepath.ToSlash(dataset.Name)
		isClassFeats := strings.HasPrefix(name, "classes/feats/")
		if name != "feat" && name != "masterfeats" && name != "classes/core" && !isClassFeats {
			continue
		}
		collected, err := collectNativeDataset(dataset)
		if err != nil {
			return
		}
		for key, id := range collected.LockData {
			keyToID[key] = id
		}
		switch {
		case name == "feat":
			featRowByKey = rowsByKey(collected.Rows)
		case isClassFeats:
			classTables = append(classTables, classFeatTable{
				path:     dataset.BasePath,
				classKey: "classes:" + name[strings.LastIndex(name, "/")+1:],
				rows:     collected.Rows,
			})
		}
	}
	if featRowByKey == nil {
		return
	}
	for _, table := range classTables {
		for _, row := range table.rows {
			featRef, ok := row["FeatIndex"].(map[string]any)
			if !ok {
				continue
			}
			refKey, _ := featRef["id"].(string)
			if !strings.HasPrefix(refKey, "masterfeats:") {
				continue
			}
			masterfeatKey := resolveCanonicalDatasetKey(refKey, keyToID)
			if _, ok := keyToID[masterfeatKey]; !ok {
				continue
			}
			featKeys := make([]string, 0, len(featRowByKey))
			for featKey := range featRowByKey {
				if strings.HasPrefix(featKey, "feat:") {
					featKeys = append(featKeys, featKey)
				}
			}
			slices.Sort(featKeys)
			for _, featKey := range featKeys {
				featRow := featRowByKey[featKey]
				if !rowReferencesMasterfeat(featRow, masterfeatKey, keyToID) {
					continue
				}
				if classFeatExpansionCanUseFeat(featRow, table.classKey, keyToID) {
					continue
				}
				if minLevelClass, ok := lookupField(featRow, "MinLevelClass"); ok && !isNullishValue(minLevelClass) {
					continue
				}
				report.Diagnostics = append(report.Diagnostics, Diagnostic{
					Severity: SeverityWarning,
					Path:     table.path,
					Message: fmt.Sprintf(
						"%s references %s but %s is excluded from expansion (ALLCLASSESCANUSE=0 with no MinLevelClass makes it unobtainable); override ALLCLASSESCANUSE or set MinLevelClass",
						table.classKey, masterfeatKey, featKey),
				})
			}
		}
	}
}