package store

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"time"
)

// Tool — one act in the allowlist. Scope namespaces tools (e.g. "homelab").
// Cmd is the fixed argv prefix run with the utterance's args appended (no
// shell). Status 'proposed' is a scaffold that drives nothing; 'enabled' is
// the human-flipped, runnable form.
type Tool struct {
	Name        string
	Scope       string
	Cmd         []string
	Destructive bool
	Status      string // proposed | enabled
	Utterance   string // provenance: the utterance that scaffolded a proposal
	CreatedTs   time.Time
	UpdatedTs   time.Time
}

var (
	// ErrToolNotFound — no tool row with this name.
	ErrToolNotFound = errors.New("store: tool not found")
	// ErrToolCmd — an enable supplied an empty argv (an enabled tool must run something).
	ErrToolCmd = errors.New("store: enabled tool needs a non-empty cmd")
)

// ProposeTool inserts a 'proposed' scaffold for name (provenance = utterance)
// if no row for name exists yet. Returns true when a new proposal was written,
// false when a row (proposed or enabled) already existed. maven calls this when
// she classifies an act whose verb isn't on the enabled allowlist — she drafts
// the registration; a human enables it. Never overwrites an enabled tool.
// scope defaults to "homelab" when empty.
func (s *Store) ProposeTool(ctx context.Context, name, utterance, scope string, ts time.Time) (bool, error) {
	if scope == "" {
		scope = "homelab"
	}
	res, err := s.db.ExecContext(ctx, `
		INSERT INTO tools (name, scope, cmd, destructive, status, utterance, created_ts, updated_ts)
		VALUES (?, ?, '[]', 0, 'proposed', ?, ?, ?)
		ON CONFLICT(name) DO NOTHING`,
		name, scope, utterance, ts.UnixMilli(), ts.UnixMilli())
	if err != nil {
		return false, fmt.Errorf("propose tool: %w", err)
	}
	n, err := res.RowsAffected()
	if err != nil {
		return false, fmt.Errorf("propose tool: rows affected: %w", err)
	}
	return n > 0, nil
}

// EnableTool fills cmd + destructive and flips status to 'enabled'. This is the
// human "enable" act (the authed surface calls it); it upserts so enabling a
// name that was never proposed still works. An empty cmd is refused — an
// enabled tool that runs nothing is a footgun, not a tool.
// scope defaults to "homelab" when empty.
func (s *Store) EnableTool(ctx context.Context, name string, cmd []string, destructive bool, scope string, ts time.Time) error {
	if len(cmd) == 0 {
		return ErrToolCmd
	}
	if scope == "" {
		scope = "homelab"
	}
	raw, err := json.Marshal(cmd)
	if err != nil {
		return fmt.Errorf("enable tool: %w", err)
	}
	d := 0
	if destructive {
		d = 1
	}
	_, err = s.db.ExecContext(ctx, `
		INSERT INTO tools (name, scope, cmd, destructive, status, utterance, created_ts, updated_ts)
		VALUES (?, ?, ?, ?, 'enabled', '', ?, ?)
		ON CONFLICT(name) DO UPDATE SET scope=excluded.scope, cmd=excluded.cmd, destructive=excluded.destructive,
			status='enabled', updated_ts=excluded.updated_ts`,
		name, scope, string(raw), d, ts.UnixMilli(), ts.UnixMilli())
	if err != nil {
		return fmt.Errorf("enable tool: %w", err)
	}
	return nil
}

// DeleteTool permanently removes a tool row. Used for "dismiss" on proposed
// tools — there's no dismissed status, the proposal is simply gone and maven
// can re-propose it later if the same gap is encountered. Idempotent: deleting
// a tool that doesn't exist is a no-op.
func (s *Store) DeleteTool(ctx context.Context, name string) error {
	_, err := s.db.ExecContext(ctx, `DELETE FROM tools WHERE name = ?`, name)
	return err
}

// DisableTool sets a tool's status from 'enabled' back to 'proposed'. This is
// the "disable" act on the authed surface — the tool stays in the store (its
// provenance preserved) but won't run until re-enabled. Idempotent: disabling
// a tool that is already proposed or doesn't exist is a no-op.
func (s *Store) DisableTool(ctx context.Context, name string) error {
	_, err := s.db.ExecContext(ctx,
		`UPDATE tools SET status = 'proposed', updated_ts = ? WHERE name = ? AND status = 'enabled'`,
		time.Now().UnixMilli(), name)
	if err != nil {
		return fmt.Errorf("disable tool: %w", err)
	}
	return nil
}

// LookupTool returns the tool by name. ErrToolNotFound when absent.
func (s *Store) LookupTool(ctx context.Context, name string) (Tool, error) {
	row := s.db.QueryRowContext(ctx, `
		SELECT name, scope, cmd, destructive, status, utterance, created_ts, updated_ts
		  FROM tools WHERE name = ?`, name)
	t, err := scanTool(row)
	if errors.Is(err, sql.ErrNoRows) {
		return Tool{}, ErrToolNotFound
	}
	return t, err
}

// ListTools returns tools filtered by status ("" ⇒ all), name-sorted.
func (s *Store) ListTools(ctx context.Context, status string) ([]Tool, error) {
	q := `SELECT name, scope, cmd, destructive, status, utterance, created_ts, updated_ts FROM tools`
	var args []any
	if status != "" {
		q += ` WHERE status = ?`
		args = append(args, status)
	}
	q += ` ORDER BY name ASC`
	rows, err := s.db.QueryContext(ctx, q, args...)
	if err != nil {
		return nil, fmt.Errorf("list tools: %w", err)
	}
	defer rows.Close()
	var out []Tool
	for rows.Next() {
		t, err := scanTool(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, t)
	}
	return out, rows.Err()
}

// scanner is the shared shape of *sql.Row and *sql.Rows.
type scanner interface{ Scan(...any) error }

func scanTool(sc scanner) (Tool, error) {
	var t Tool
	var cmdJSON string
	var d int
	var created, updated int64
	if err := sc.Scan(&t.Name, &t.Scope, &cmdJSON, &d, &t.Status, &t.Utterance, &created, &updated); err != nil {
		return Tool{}, err
	}
	if err := json.Unmarshal([]byte(cmdJSON), &t.Cmd); err != nil {
		return Tool{}, fmt.Errorf("scan tool %q cmd: %w", t.Name, err)
	}
	t.Destructive = d != 0
	t.CreatedTs = time.UnixMilli(created).UTC()
	t.UpdatedTs = time.UnixMilli(updated).UTC()
	return t, nil
}