package store

import "strings"

const (
	DohPolicyPrimaryOnly = "primary_only"
	DohPolicyFailover    = "failover"
	DohPolicyUnion       = "union"
)

// NormalizeDohResolverPolicy returns a supported resolver policy name.
func NormalizeDohResolverPolicy(policy string) string {
	switch strings.TrimSpace(policy) {
	case DohPolicyFailover, DohPolicyUnion:
		return strings.TrimSpace(policy)
	default:
		return DohPolicyPrimaryOnly
	}
}

// NormalizeDohProfileIDList deduplicates profile ids preserving order.
func NormalizeDohProfileIDList(ids []string) []string {
	if len(ids) == 0 {
		return nil
	}
	seen := make(map[string]struct{}, len(ids))
	out := make([]string, 0, len(ids))
	for _, id := range ids {
		id = strings.TrimSpace(id)
		if id == "" {
			continue
		}
		if _, ok := seen[id]; ok {
			continue
		}
		seen[id] = struct{}{}
		out = append(out, id)
	}
	if len(out) == 0 {
		return nil
	}
	return out
}

// EffectiveDohProfileIDs returns ordered DoH profile ids for a module.
func (m *Module) EffectiveDohProfileIDs() []string {
	if m == nil {
		return nil
	}
	if ids := NormalizeDohProfileIDList(m.DohProfileIDs); len(ids) > 0 {
		return ids
	}
	if m.DohProfileID != nil {
		if id := strings.TrimSpace(*m.DohProfileID); id != "" {
			return []string{id}
		}
	}
	return nil
}

// SyncLegacyDohProfileID keeps deprecated doh_profile_id aligned with the first profile.
func (m *Module) SyncLegacyDohProfileID() {
	if m == nil {
		return
	}
	ids := NormalizeDohProfileIDList(m.DohProfileIDs)
	if len(ids) == 0 {
		m.DohProfileID = nil
		return
	}
	first := ids[0]
	m.DohProfileID = &first
}

// NormalizeModuleDoh fills doh_profile_ids, policy and legacy id from module input.
func NormalizeModuleDoh(m *Module) {
	if m == nil {
		return
	}
	ids := NormalizeDohProfileIDList(m.DohProfileIDs)
	if len(ids) == 0 && m.DohProfileID != nil {
		if id := strings.TrimSpace(*m.DohProfileID); id != "" {
			ids = []string{id}
		}
	}
	m.DohProfileIDs = ids
	m.DohResolverPolicy = NormalizeDohResolverPolicy(m.DohResolverPolicy)
	m.SyncLegacyDohProfileID()
}

// ApplyModuleDohPatch merges DoH-related fields from patch into mod.
func ApplyModuleDohPatch(mod *Module, patch *ModulePatch) {
	if mod == nil || patch == nil {
		return
	}
	if patch.DohProfileIDs != nil {
		mod.DohProfileIDs = NormalizeDohProfileIDList(*patch.DohProfileIDs)
	} else if patch.DohProfileID != nil {
		v := strings.TrimSpace(*patch.DohProfileID)
		if v == "" {
			mod.DohProfileIDs = nil
		} else {
			mod.DohProfileIDs = []string{v}
		}
	}
	if patch.DohResolverPolicy != nil {
		mod.DohResolverPolicy = NormalizeDohResolverPolicy(*patch.DohResolverPolicy)
	}
	mod.SyncLegacyDohProfileID()
}