// Package tool is maven's act executor: it runs the ENABLED tools from the
// store's allowlist, and drafts 'proposed' scaffolds for acts that aren't on
// it yet.
//
// Boundary discipline (DESIGN.md § "Tool registration — drafting is suggest,
// enabling is act"):
//
//   - The store is the allowlist. Only status='enabled' rows run. A verb not
//     on it → refuse ("not on the list → refuse, don't improvise") and draft a
//     'proposed' scaffold instead. Enabling a proposal is a human act on an
//     authed surface (mavweb), gated at AuthStepUp — never the voice path, so
//     a compromised router can't grant itself a capability.
//   - Args are passed as argv, NEVER through a shell. STT text lands as
//     positional arguments to Cmd; there is no `sh -c`, so "restart nginx;
//     rm -rf" can't inject — the tail is one argv element to the named binary.
//   - Destructive tools don't run on first hearing: Exec returns ErrNeedsConfirm
//     and the handler runs a confirm turn ("выполнить X? да/нет"); only a
//     confirmed re-Exec runs them. A gate assumes a fully-formed action, which
//     an enabled+matched act is (DESIGN.md § "Confirmation is not one
//     mechanism").
package tool

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"log"
	"os/exec"
	"strings"
	"time"

	"github.com/kami/maven/internal/ipc"
	"github.com/kami/maven/internal/router"
)

// API — the narrow slice of ipc.CoreAPI the executor and matcher need. Backed
// in-process by the daemon's store adapter (a direct sqlite query per call —
// acts are rare, personal-scale; no cache).
type API interface {
	LookupTool(ctx context.Context, name string) (ipc.Tool, error)
	ListTools(ctx context.Context, status string) ([]ipc.Tool, error)
	ProposeTool(ctx context.Context, name, utterance, scope string, ts time.Time) (bool, error)
}

var (
	// ErrNotEnabled — the fn isn't an enabled tool (absent, or still proposed).
	ErrNotEnabled = errors.New("tool not on the enabled allowlist")
	// ErrNeedsConfirm — the fn is enabled but destructive; needs a confirm turn.
	ErrNeedsConfirm = errors.New("destructive tool needs confirmation")
)

// Executor runs enabled tools. run is the exec seam (default: real process);
// tests swap it. timeout bounds each invocation.
type Executor struct {
	api     API
	timeout time.Duration
	run     func(ctx context.Context, argv []string) (string, error)
}

// NewExecutor builds the executor. timeout<=0 defaults to 30s.
func NewExecutor(api API, timeout time.Duration) *Executor {
	if timeout <= 0 {
		timeout = 30 * time.Second
	}
	return &Executor{api: api, timeout: timeout, run: runProcess}
}

// Exec looks up name in the store and runs Cmd+args as argv (no shell).
// confirmed=true is the second turn of a destructive act (the user said "да");
// it bypasses the ErrNeedsConfirm gate. Non-enabled ⇒ ErrNotEnabled; a
// destructive tool with confirmed=false ⇒ ErrNeedsConfirm.
func (e *Executor) Exec(ctx context.Context, name string, args []string, confirmed bool) (string, error) {
	t, err := e.api.LookupTool(ctx, name)
	if errors.Is(err, ipc.ErrToolNotFound) {
		return "", ErrNotEnabled
	}
	if err != nil {
		return "", err
	}
	if t.Status != "enabled" {
		return "", ErrNotEnabled
	}
	if t.Destructive && !confirmed {
		return "", ErrNeedsConfirm
	}
	argv := append(append([]string(nil), t.Cmd...), args...)
	if len(argv) == 0 {
		return "", ErrNotEnabled
	}
	ctx, cancel := context.WithTimeout(ctx, e.timeout)
	defer cancel()
	return e.run(ctx, argv)
}

func runProcess(ctx context.Context, argv []string) (string, error) {
	cmd := exec.CommandContext(ctx, argv[0], argv[1:]...)
	var buf bytes.Buffer
	cmd.Stdout = &buf
	cmd.Stderr = &buf
	err := cmd.Run()
	out := strings.TrimSpace(buf.String())
	if err != nil {
		return out, fmt.Errorf("run %v: %w", argv, err)
	}
	return out, nil
}

// Matcher — a router.ActMatcher whose allowlist is the live set of enabled
// tool names (one source of truth with the executor). Match delegates to the
// router's default prefix logic over the current names. The interface's Match
// has no ctx, so it queries with a background context — an in-process sqlite
// read on the daemon.
type Matcher struct{ api API }

// NewMatcher builds a store-backed act matcher.
func NewMatcher(api API) *Matcher { return &Matcher{api: api} }

func (m *Matcher) names() []string {
	ts, err := m.api.ListTools(context.Background(), "enabled")
	if err != nil {
		log.Printf("tool: list enabled tools: %v", err)
		return nil
	}
	names := make([]string, len(ts))
	for i, t := range ts {
		names[i] = t.Name
	}
	return names
}

// Allowlist — the enabled verbs (for stage-0 grammar wiring / introspection).
func (m *Matcher) Allowlist() []string { return m.names() }

// Match — longest-verb-first prefix match over the live enabled allowlist.
func (m *Matcher) Match(utterance string) (string, []string, bool) {
	return router.DefaultActMatcher{Fns: m.names()}.Match(utterance)
}