package tools

import (
	"context"
	"encoding/json"
)

// aliasTool exposes an existing tool under a pi-style name.
type aliasTool struct {
	name  string
	inner Tool
}

func (a aliasTool) Name() string                 { return a.name }
func (a aliasTool) Description() string          { return a.inner.Description() }
func (a aliasTool) Parameters() json.RawMessage  { return a.inner.Parameters() }
func (a aliasTool) Execute(ctx context.Context, args json.RawMessage) (Result, error) {
	return a.inner.Execute(ctx, args)
}

// piAliases maps the headless pi tool name onto the name already registered.
var piAliases = map[string]string{
	"read":  "read_file",
	"write": "write_file",
	"edit":  "edit_file",
	"bash":  "run_command",
	"grep":  "grep",
	"find":  "glob",
	"ls":    "list_dir",
}

// RegisterPiAliases adds pi tool names beside the existing ones.
// A name is skipped when the underlying tool is not registered.
func (r *Registry) RegisterPiAliases() {
	for alias, inner := range piAliases {
		if alias == inner || r.Has(alias) || !r.Has(inner) {
			continue
		}
		r.Register(aliasTool{name: alias, inner: r.tools[inner]})
	}
}

// FilterOptions selects which tools stay visible.
type FilterOptions struct {
	Tools     []string
	Exclude   []string
	NoBuiltin bool
}

// Filter applies an allow list, then exclusions. NoBuiltin drops the
// workspace tool names and their pi aliases.
func (r *Registry) Filter(opts FilterOptions) error {
	if len(opts.Tools) > 0 {
		if err := r.Restrict(opts.Tools); err != nil {
			return err
		}
	}
	drop := map[string]bool{}
	for _, name := range opts.Exclude {
		drop[name] = true
	}
	if opts.NoBuiltin {
		for _, name := range []string{"read_file", "write_file", "edit_file", "multi_edit", "list_dir", "grep", "glob", "run_command", "run_python"} {
			drop[name] = true
		}
		for alias := range piAliases {
			drop[alias] = true
		}
	}
	if len(drop) == 0 {
		return nil
	}
	var order []string
	for _, name := range r.order {
		if drop[name] {
			delete(r.tools, name)
			continue
		}
		order = append(order, name)
	}
	r.order = order
	return nil
}