package tools

import (
	"context"
	"encoding/json"
	"fmt"
	"sort"

	"agentu/internal/llm"
)

const MaxToolOutputBytes = 64 * 1024

type Tool interface {
	Definition() llm.Tool
	Execute(ctx context.Context, args json.RawMessage) (string, error)
}

type Registry struct {
	tools   map[string]Tool
	primary []string
}

func NewRegistry(items ...Tool) *Registry {
	r := &Registry{tools: make(map[string]Tool, len(items))}
	for _, item := range items {
		r.Register(item)
	}
	return r
}

func (r *Registry) Register(tool Tool) {
	name := tool.Definition().Function.Name
	if _, exists := r.tools[name]; !exists {
		r.primary = append(r.primary, name)
	}
	r.tools[name] = tool
}

func (r *Registry) RegisterAlias(alias string, tool Tool) {
	r.tools[alias] = tool
}

func (r *Registry) Get(name string) (Tool, bool) {
	tool, ok := r.tools[name]
	return tool, ok
}

func (r *Registry) Definitions() []llm.Tool {
	defs := make([]llm.Tool, 0, len(r.primary))
	for _, name := range r.primary {
		tool := r.tools[name]
		defs = append(defs, tool.Definition())
	}
	sort.Slice(defs, func(i, j int) bool {
		return defs[i].Function.Name < defs[j].Function.Name
	})
	return defs
}

func ReadOnlyBuiltins(workingDir string) *Registry {
	fileRead := NewFileReadTool(workingDir)
	fileList := NewFileListTool(workingDir)
	fileSearch := NewFileSearchTool(workingDir)

	registry := NewRegistry(fileRead, fileList, fileSearch)
	registry.RegisterAlias("file.read", fileRead)
	registry.RegisterAlias("file.list", fileList)
	registry.RegisterAlias("file.search", fileSearch)
	return registry
}

func Builtins(workingDir string) *Registry {
	registry := ReadOnlyBuiltins(workingDir)
	fileWrite := NewFileWriteTool(workingDir)
	shellRun := NewShellRunTool(workingDir)
	registry.Register(fileWrite)
	registry.Register(shellRun)
	registry.RegisterAlias("file.write", fileWrite)
	registry.RegisterAlias("shell.run", shellRun)
	return registry
}

func AgentInstructions(workingDir string, yolo bool) string {
	if yolo {
		return fmt.Sprintf(`Local project context:
- The project working directory is %q.
- Tools are available, but use them only when needed to satisfy the user's request.
- Do not call tools for greetings, small talk, simple Q&A, or general questions that do not require local project or command context.
- Do not explore the project preemptively. Do not call file_list just to discover context unless the user asks about project files or the answer truly depends on local files.
- When the user asks to inspect, list, search, or read project files, use file_list, file_search, and file_read instead of saying you cannot access local files.
- When the user asks to run, execute, test, check, debug, or inspect a shell command, use shell_run. This includes local commands written in backticks, such as go, make, git, pwd, ls, ps, and similar terminal commands.
- Do not use file tools as a substitute for a command execution request.
- Do not start interactive or long-running sessions. Prefer bounded, non-interactive local commands with clear completion conditions.
- Tool paths should normally be relative to the project working directory.
- Available tools: file_list, file_read, file_search, file_write, shell_run.`, workingDir)
	}
	return fmt.Sprintf(`Local project context:
- The project working directory is %q.
- Read-only project file tools are available, but use them only when needed to satisfy the user's request.
- Do not call tools for greetings, small talk, simple Q&A, or general questions that do not require local project context.
- Do not explore the project preemptively. Do not call file_list just to discover context unless the user asks about project files or the answer truly depends on local files.
- When the user asks to inspect, list, search, or read project files, use file_list, file_search, and file_read instead of saying you cannot access local files.
- Shell command execution is disabled in this mode. When the user asks to run, execute, test, check, debug, or inspect a shell command, do not use file tools as a substitute; explain that they need to restart agentu with --yolo to enable shell_run.
- Tool paths should normally be relative to the project working directory.
- Available tools: file_list, file_read, file_search.`, workingDir)
}

func JSONSchema(schema string) json.RawMessage {
	return json.RawMessage(schema)
}

func FormatResult(output string) string {
	if len(output) <= MaxToolOutputBytes {
		return output
	}
	return output[:MaxToolOutputBytes] + fmt.Sprintf("\n\n[truncated after %d bytes]", MaxToolOutputBytes)
}

func FormatError(err error) string {
	return "error: " + err.Error()
}