package vaultview

import (
	"slices"

	"git.julianfamily.org/keepassgo/internal/vault"
)

const KeepassRoot = "keepass"
const TemplatesRoot = "Templates"

// View projects the physical vault model into a logical tree for a specific
// product surface.
type View interface {
	ChildGroups(path []string) []string
	EntriesInPath(path []string) []vault.Entry
	EntriesUnderPath(path []string) []vault.Entry
	ToPhysicalPath(path []string) []string
	FromPhysicalPath(path []string) []string
	ToPhysicalEntry(entry vault.Entry) vault.Entry
	FromPhysicalEntry(entry vault.Entry) vault.Entry
}

// Vault returns the physical datastore view.
func Vault(model vault.Model) View {
	return physicalView{model: model}
}

// VaultRoot returns the logical main-vault view rooted at the physical
// keepass storage group.
func VaultRoot(model vault.Model) View {
	return prefixedView{model: model, root: KeepassRoot, rooted: usesTopLevelRoot(model, KeepassRoot)}
}

// VaultTemplates returns the logical templates view rooted at the physical
// Templates storage group.
func VaultTemplates(model vault.Model) View {
	return templatesView{model: model}
}

// VaultRecycleBin returns the logical recycle-bin view.
func VaultRecycleBin(model vault.Model) View {
	return recycleBinView{model: model}
}

type physicalView struct {
	model vault.Model
}

func (v physicalView) ChildGroups(path []string) []string {
	return v.model.ChildGroups(path)
}

func (v physicalView) EntriesInPath(path []string) []vault.Entry {
	return cloneEntries(v.model.EntriesInPath(path))
}

func (v physicalView) EntriesUnderPath(path []string) []vault.Entry {
	return cloneEntries(v.model.EntriesUnderPath(path))
}

func (v physicalView) ToPhysicalPath(path []string) []string {
	return clonePath(path)
}

func (v physicalView) FromPhysicalPath(path []string) []string {
	return clonePath(path)
}

func (v physicalView) ToPhysicalEntry(entry vault.Entry) vault.Entry {
	return cloneEntry(entry)
}

func (v physicalView) FromPhysicalEntry(entry vault.Entry) vault.Entry {
	return cloneEntry(entry)
}

type prefixedView struct {
	model  vault.Model
	root   string
	rooted bool
}

func (v prefixedView) ChildGroups(path []string) []string {
	return v.model.ChildGroups(v.ToPhysicalPath(path))
}

func (v prefixedView) EntriesInPath(path []string) []vault.Entry {
	return v.mapEntries(v.model.EntriesInPath(v.ToPhysicalPath(path)))
}

func (v prefixedView) EntriesUnderPath(path []string) []vault.Entry {
	return v.mapEntries(v.model.EntriesUnderPath(v.ToPhysicalPath(path)))
}

func (v prefixedView) ToPhysicalPath(path []string) []string {
	if !v.rooted {
		return clonePath(path)
	}
	if len(path) == 0 {
		return []string{v.root}
	}
	return append([]string{v.root}, clonePath(path)...)
}

func (v prefixedView) FromPhysicalPath(path []string) []string {
	if !v.rooted {
		return clonePath(path)
	}
	if len(path) == 0 {
		return nil
	}
	if path[0] != v.root {
		return clonePath(path)
	}
	return clonePath(path[1:])
}

func (v prefixedView) ToPhysicalEntry(entry vault.Entry) vault.Entry {
	entry = cloneEntry(entry)
	entry.Path = v.ToPhysicalPath(entry.Path)
	for i := range entry.History {
		entry.History[i].Path = v.ToPhysicalPath(entry.History[i].Path)
	}
	return entry
}

func (v prefixedView) FromPhysicalEntry(entry vault.Entry) vault.Entry {
	entry = cloneEntry(entry)
	entry.Path = v.FromPhysicalPath(entry.Path)
	for i := range entry.History {
		entry.History[i].Path = v.FromPhysicalPath(entry.History[i].Path)
	}
	return entry
}

func (v prefixedView) mapEntries(entries []vault.Entry) []vault.Entry {
	out := make([]vault.Entry, 0, len(entries))
	for _, entry := range entries {
		out = append(out, v.FromPhysicalEntry(entry))
	}
	return out
}

type recycleBinView struct {
	model vault.Model
}

type templatesView struct {
	model vault.Model
}

func (v templatesView) ChildGroups(path []string) []string {
	return groupChildren(templateGroupPaths(v.model), v.EntriesUnderPath(nil), path)
}

func (v templatesView) EntriesInPath(path []string) []vault.Entry {
	return entriesInPath(v.EntriesUnderPath(nil), path)
}

func (v templatesView) EntriesUnderPath(path []string) []vault.Entry {
	var out []vault.Entry
	for _, entry := range v.model.Templates {
		if len(path) > len(entry.Path) {
			continue
		}
		physical := entry.Path
		if len(physical) > 0 && physical[0] == TemplatesRoot {
			physical = physical[1:]
		}
		if len(path) > len(physical) {
			continue
		}
		if !slices.Equal(physical[:len(path)], path) {
			continue
		}
		item := cloneEntry(entry)
		item.Path = clonePath(physical)
		for i := range item.History {
			item.History[i].Path = v.FromPhysicalPath(item.History[i].Path)
		}
		out = append(out, item)
	}
	slices.SortFunc(out, func(a, b vault.Entry) int {
		switch {
		case a.Title < b.Title:
			return -1
		case a.Title > b.Title:
			return 1
		default:
			return 0
		}
	})
	return out
}

func (v templatesView) ToPhysicalPath(path []string) []string {
	if len(path) == 0 {
		return []string{TemplatesRoot}
	}
	return append([]string{TemplatesRoot}, clonePath(path)...)
}

func (v templatesView) FromPhysicalPath(path []string) []string {
	if len(path) == 0 {
		return nil
	}
	if path[0] != TemplatesRoot {
		return clonePath(path)
	}
	return clonePath(path[1:])
}

func (v templatesView) ToPhysicalEntry(entry vault.Entry) vault.Entry {
	entry = cloneEntry(entry)
	entry.Path = v.ToPhysicalPath(entry.Path)
	for i := range entry.History {
		entry.History[i].Path = v.ToPhysicalPath(entry.History[i].Path)
	}
	return entry
}

func (v templatesView) FromPhysicalEntry(entry vault.Entry) vault.Entry {
	entry = cloneEntry(entry)
	entry.Path = v.FromPhysicalPath(entry.Path)
	for i := range entry.History {
		entry.History[i].Path = v.FromPhysicalPath(entry.History[i].Path)
	}
	return entry
}

func (v recycleBinView) ChildGroups(path []string) []string {
	return childGroups(v.model.RecycleBin, path)
}

func (v recycleBinView) EntriesInPath(path []string) []vault.Entry {
	return entriesInPath(v.model.RecycleBin, path)
}

func (v recycleBinView) EntriesUnderPath(path []string) []vault.Entry {
	var out []vault.Entry
	for _, entry := range v.model.RecycleBin {
		if len(path) > len(entry.Path) {
			continue
		}
		if !slices.Equal(entry.Path[:len(path)], path) {
			continue
		}
		out = append(out, cloneEntry(entry))
	}
	slices.SortFunc(out, func(a, b vault.Entry) int {
		switch {
		case a.Title < b.Title:
			return -1
		case a.Title > b.Title:
			return 1
		default:
			return 0
		}
	})
	return out
}

func (v recycleBinView) ToPhysicalPath(path []string) []string {
	return clonePath(path)
}

func (v recycleBinView) FromPhysicalPath(path []string) []string {
	return clonePath(path)
}

func (v recycleBinView) ToPhysicalEntry(entry vault.Entry) vault.Entry {
	return cloneEntry(entry)
}

func (v recycleBinView) FromPhysicalEntry(entry vault.Entry) vault.Entry {
	return cloneEntry(entry)
}

func childGroups(entries []vault.Entry, path []string) []string {
	return groupChildren(nil, entries, path)
}

func groupChildren(groupPaths [][]string, entries []vault.Entry, path []string) []string {
	seen := map[string]bool{}
	var groups []string
	for _, entry := range entries {
		if len(path) > len(entry.Path) {
			continue
		}
		if !slices.Equal(entry.Path[:len(path)], path) {
			continue
		}
		if len(entry.Path) == len(path) {
			continue
		}
		group := entry.Path[len(path)]
		if seen[group] {
			continue
		}
		seen[group] = true
		groups = append(groups, group)
	}
	for _, groupPath := range groupPaths {
		if len(path) > len(groupPath) {
			continue
		}
		if !slices.Equal(groupPath[:len(path)], path) {
			continue
		}
		if len(groupPath) == len(path) {
			continue
		}
		group := groupPath[len(path)]
		if seen[group] {
			continue
		}
		seen[group] = true
		groups = append(groups, group)
	}
	slices.Sort(groups)
	return groups
}

func entriesInPath(entries []vault.Entry, path []string) []vault.Entry {
	var out []vault.Entry
	for _, entry := range entries {
		if slices.Equal(entry.Path, path) {
			out = append(out, cloneEntry(entry))
		}
	}
	slices.SortFunc(out, func(a, b vault.Entry) int {
		switch {
		case a.Title < b.Title:
			return -1
		case a.Title > b.Title:
			return 1
		default:
			return 0
		}
	})
	return out
}

func cloneEntries(entries []vault.Entry) []vault.Entry {
	if len(entries) == 0 {
		return nil
	}
	out := make([]vault.Entry, len(entries))
	for i := range entries {
		out[i] = cloneEntry(entries[i])
	}
	return out
}

func cloneEntry(entry vault.Entry) vault.Entry {
	entry.Path = clonePath(entry.Path)
	entry.Tags = slices.Clone(entry.Tags)
	if entry.Fields != nil {
		fields := make(map[string]string, len(entry.Fields))
		for key, value := range entry.Fields {
			fields[key] = value
		}
		entry.Fields = fields
	}
	if entry.Attachments != nil {
		attachments := make(map[string][]byte, len(entry.Attachments))
		for key, value := range entry.Attachments {
			attachments[key] = slices.Clone(value)
		}
		entry.Attachments = attachments
	}
	if len(entry.History) != 0 {
		history := make([]vault.Entry, len(entry.History))
		for i := range entry.History {
			history[i] = cloneEntry(entry.History[i])
		}
		entry.History = history
	}
	return entry
}

func clonePath(path []string) []string {
	if len(path) == 0 {
		return nil
	}
	return slices.Clone(path)
}

func templateGroupPaths(model vault.Model) [][]string {
	var out [][]string
	for _, group := range model.Groups {
		if len(group) == 0 || group[0] != TemplatesRoot {
			continue
		}
		out = append(out, clonePath(group[1:]))
	}
	return out
}

func usesTopLevelRoot(model vault.Model, root string) bool {
	if len(model.Entries) == 0 && len(model.Groups) == 0 && len(model.RecycleBin) == 0 {
		return root == KeepassRoot
	}
	return groupsUseRoot(model.Groups, root) ||
		entriesUseRoot(model.Entries, root) ||
		entriesUseRoot(model.Templates, root) ||
		entriesUseRoot(model.RecycleBin, root)
}

func groupsUseRoot(groups [][]string, root string) bool {
	for _, group := range groups {
		if len(group) > 0 && group[0] == root {
			return true
		}
	}
	return false
}

func entriesUseRoot(entries []vault.Entry, root string) bool {
	for _, entry := range entries {
		if len(entry.Path) > 0 && entry.Path[0] == root {
			return true
		}
	}
	return false
}