// primitiveObjectDiff returns a diff of the passed objects' primitive fields.
// The filter field can be used to exclude fields from the diff. The name is the
// name of the objects. If contextual is set, non-changed fields will also be
// stored in the object diff.
func primitiveObjectDiff(old, new interface{}, filter []string, name string, contextual bool) *ObjectDiff {
	oldPrimitiveFlat := flatmap.Flatten(old, filter, true)
	newPrimitiveFlat := flatmap.Flatten(new, filter, true)
	delete(oldPrimitiveFlat, "")
	delete(newPrimitiveFlat, "")

	diff := &ObjectDiff{Name: name}
	diff.Fields = fieldDiffs(oldPrimitiveFlat, newPrimitiveFlat, contextual)

	var added, deleted, edited bool
	for _, f := range diff.Fields {
		switch f.Type {
		case DiffTypeEdited:
			edited = true
			break
		case DiffTypeDeleted:
			deleted = true
		case DiffTypeAdded:
			added = true
		}
	}

	if edited || added && deleted {
		diff.Type = DiffTypeEdited
	} else if added {
		diff.Type = DiffTypeAdded
	} else if deleted {
		diff.Type = DiffTypeDeleted
	} else {
		return nil
	}

	return diff
}

// serviceDiff returns the diff of two service objects. If contextual diff is
// enabled, all fields will be returned, even if no diff occurred.
func serviceDiff(old, new *Service, contextual bool) *ObjectDiff {
	diff := &ObjectDiff{Type: DiffTypeNone, Name: "Service"}
	var oldPrimitiveFlat, newPrimitiveFlat map[string]string

	if reflect.DeepEqual(old, new) {
		return nil
	} else if old == nil {
		old = &Service{}
		diff.Type = DiffTypeAdded
		newPrimitiveFlat = flatmap.Flatten(new, nil, true)
	} else if new == nil {
		new = &Service{}
		diff.Type = DiffTypeDeleted
		oldPrimitiveFlat = flatmap.Flatten(old, nil, true)
	} else {
		diff.Type = DiffTypeEdited
		oldPrimitiveFlat = flatmap.Flatten(old, nil, true)
		newPrimitiveFlat = flatmap.Flatten(new, nil, true)
	}

	// Diff the primitive fields.
	diff.Fields = fieldDiffs(oldPrimitiveFlat, newPrimitiveFlat, contextual)

	// Checks diffs
	if cDiffs := serviceCheckDiffs(old.Checks, new.Checks, contextual); cDiffs != nil {
		diff.Objects = append(diff.Objects, cDiffs...)
	}

	return diff
}

// Diff returns a diff of two resource objects. If contextual diff is enabled,
// non-changed fields will still be returned.
func (r *Resources) Diff(other *Resources, contextual bool) *ObjectDiff {
	diff := &ObjectDiff{Type: DiffTypeNone, Name: "Resources"}
	var oldPrimitiveFlat, newPrimitiveFlat map[string]string

	if reflect.DeepEqual(r, other) {
		return nil
	} else if r == nil {
		r = &Resources{}
		diff.Type = DiffTypeAdded
		newPrimitiveFlat = flatmap.Flatten(other, nil, true)
	} else if other == nil {
		other = &Resources{}
		diff.Type = DiffTypeDeleted
		oldPrimitiveFlat = flatmap.Flatten(r, nil, true)
	} else {
		diff.Type = DiffTypeEdited
		oldPrimitiveFlat = flatmap.Flatten(r, nil, true)
		newPrimitiveFlat = flatmap.Flatten(other, nil, true)
	}

	// Diff the primitive fields.
	diff.Fields = fieldDiffs(oldPrimitiveFlat, newPrimitiveFlat, contextual)

	// Network Resources diff
	if nDiffs := networkResourceDiffs(r.Networks, other.Networks, contextual); nDiffs != nil {
		diff.Objects = append(diff.Objects, nDiffs...)
	}

	return diff
}

// vaultDiff returns the diff of two vault objects. If contextual diff is
// enabled, all fields will be returned, even if no diff occurred.
func vaultDiff(old, new *Vault, contextual bool) *ObjectDiff {
	diff := &ObjectDiff{Type: DiffTypeNone, Name: "Vault"}
	var oldPrimitiveFlat, newPrimitiveFlat map[string]string

	if reflect.DeepEqual(old, new) {
		return nil
	} else if old == nil {
		old = &Vault{}
		diff.Type = DiffTypeAdded
		newPrimitiveFlat = flatmap.Flatten(new, nil, true)
	} else if new == nil {
		new = &Vault{}
		diff.Type = DiffTypeDeleted
		oldPrimitiveFlat = flatmap.Flatten(old, nil, true)
	} else {
		diff.Type = DiffTypeEdited
		oldPrimitiveFlat = flatmap.Flatten(old, nil, true)
		newPrimitiveFlat = flatmap.Flatten(new, nil, true)
	}

	// Diff the primitive fields.
	diff.Fields = fieldDiffs(oldPrimitiveFlat, newPrimitiveFlat, contextual)

	// Policies diffs
	if setDiff := stringSetDiff(old.Policies, new.Policies, "Policies", contextual); setDiff != nil {
		diff.Objects = append(diff.Objects, setDiff)
	}

	return diff
}

// Diff returns a diff of two task groups. If contextual diff is enabled,
// objects' fields will be stored even if no diff occurred as long as one field
// changed.
func (tg *TaskGroup) Diff(other *TaskGroup, contextual bool) (*TaskGroupDiff, error) {
	diff := &TaskGroupDiff{Type: DiffTypeNone}
	var oldPrimitiveFlat, newPrimitiveFlat map[string]string
	filter := []string{"Name"}

	if tg == nil && other == nil {
		return diff, nil
	} else if tg == nil {
		tg = &TaskGroup{}
		diff.Type = DiffTypeAdded
		diff.Name = other.Name
		newPrimitiveFlat = flatmap.Flatten(other, filter, true)
	} else if other == nil {
		other = &TaskGroup{}
		diff.Type = DiffTypeDeleted
		diff.Name = tg.Name
		oldPrimitiveFlat = flatmap.Flatten(tg, filter, true)
	} else {
		if !reflect.DeepEqual(tg, other) {
			diff.Type = DiffTypeEdited
		}
		if tg.Name != other.Name {
			return nil, fmt.Errorf("can not diff task groups with different names: %q and %q", tg.Name, other.Name)
		}
		diff.Name = other.Name
		oldPrimitiveFlat = flatmap.Flatten(tg, filter, true)
		newPrimitiveFlat = flatmap.Flatten(other, filter, true)
	}

	// Diff the primitive fields.
	diff.Fields = fieldDiffs(oldPrimitiveFlat, newPrimitiveFlat, false)

	// Constraints diff
	conDiff := primitiveObjectSetDiff(
		interfaceSlice(tg.Constraints),
		interfaceSlice(other.Constraints),
		[]string{"str"},
		"Constraint",
		contextual)
	if conDiff != nil {
		diff.Objects = append(diff.Objects, conDiff...)
	}

	// Restart policy diff
	rDiff := primitiveObjectDiff(tg.RestartPolicy, other.RestartPolicy, nil, "RestartPolicy", contextual)
	if rDiff != nil {
		diff.Objects = append(diff.Objects, rDiff)
	}

	// Tasks diff
	tasks, err := taskDiffs(tg.Tasks, other.Tasks, contextual)
	if err != nil {
		return nil, err
	}
	diff.Tasks = tasks

	return diff, nil
}

// configDiff returns the diff of two Task Config objects. If contextual diff is
// enabled, all fields will be returned, even if no diff occurred.
func configDiff(old, new map[string]interface{}, contextual bool) *ObjectDiff {
	diff := &ObjectDiff{Type: DiffTypeNone, Name: "Config"}
	if reflect.DeepEqual(old, new) {
		return nil
	} else if len(old) == 0 {
		diff.Type = DiffTypeAdded
	} else if len(new) == 0 {
		diff.Type = DiffTypeDeleted
	} else {
		diff.Type = DiffTypeEdited
	}

	// Diff the primitive fields.
	oldPrimitiveFlat := flatmap.Flatten(old, nil, false)
	newPrimitiveFlat := flatmap.Flatten(new, nil, false)
	diff.Fields = fieldDiffs(oldPrimitiveFlat, newPrimitiveFlat, contextual)
	return diff
}

// serviceCheckDiff returns the diff of two service check objects. If contextual
// diff is enabled, all fields will be returned, even if no diff occurred.
func serviceCheckDiff(old, new *ServiceCheck, contextual bool) *ObjectDiff {
	diff := &ObjectDiff{Type: DiffTypeNone, Name: "Check"}
	var oldPrimitiveFlat, newPrimitiveFlat map[string]string

	if reflect.DeepEqual(old, new) {
		return nil
	} else if old == nil {
		old = &ServiceCheck{}
		diff.Type = DiffTypeAdded
		newPrimitiveFlat = flatmap.Flatten(new, nil, true)
	} else if new == nil {
		new = &ServiceCheck{}
		diff.Type = DiffTypeDeleted
		oldPrimitiveFlat = flatmap.Flatten(old, nil, true)
	} else {
		diff.Type = DiffTypeEdited
		oldPrimitiveFlat = flatmap.Flatten(old, nil, true)
		newPrimitiveFlat = flatmap.Flatten(new, nil, true)
	}

	// Diff the primitive fields.
	diff.Fields = fieldDiffs(oldPrimitiveFlat, newPrimitiveFlat, contextual)
	return diff
}