// internal/skills/trainer/skill.go
package trainer

import (
	"context"
	"encoding/json"

	iexec "github.com/mathiasbq/supervisor/internal/exec"
	"github.com/mathiasbq/supervisor/internal/registry"
)

// ExecutorFn is the function signature for running a worker subprocess.
type ExecutorFn func(ctx context.Context, req iexec.Request) (iexec.Result, error)

// Config holds dependencies for the trainer skill.
type Config struct {
	ReaderPrompt string
	WriterPrompt string
	DefaultModel string
	ExecutorFn   ExecutorFn
	SessionsDir  string
	BrainDir     string // root of brain/ directory; writer writes to BrainDir/training-data/
}

// Skill implements the trainer MCP tool.
type Skill struct{ cfg Config }

// New creates a new trainer Skill.
func New(cfg Config) *Skill { return &Skill{cfg: cfg} }

// Name returns the skill identifier.
func (s *Skill) Name() string { return "trainer" }

// Tools returns the MCP tool definitions for this skill.
func (s *Skill) Tools() []registry.ToolDef {
	schema := func(required []string, props map[string]any) json.RawMessage {
		b, _ := json.Marshal(map[string]any{"type": "object", "required": required, "properties": props})
		return b
	}
	return []registry.ToolDef{
		{
			Name:        "trainer",
			Description: "Extract SFT and DPO training pairs from a session log. Runs a reader→writer chain: reader identifies learning moments, writer formats and writes pairs to brain/training-data/.",
			InputSchema: schema(
				[]string{"session_id"},
				map[string]any{
					"session_id": map[string]any{"type": "string"},
					"model":      map[string]any{"type": "string"},
				},
			),
		},
	}
}