package summarize

import (
	"bytes"
	"context"
	"fmt"
	"os/exec"
	"strings"
)

// ClaudeCLI shells out to the `claude` CLI in print mode. The transcript is
// sent on stdin so we don't bump into ARG_MAX for very long services.
type ClaudeCLI struct {
	// Bin is the binary name; defaults to "claude".
	Bin string
	// Model passes through to `claude --model`. Empty leaves the CLI default.
	Model string
	// ExtraArgs are appended verbatim before the prompt arg.
	ExtraArgs []string
}

func (c *ClaudeCLI) Name() string { return "claude-cli" }

func (c *ClaudeCLI) Summarize(ctx context.Context, systemPrompt, userContent string) (string, error) {
	bin := c.Bin
	if bin == "" {
		bin = "claude"
	}
	if _, err := exec.LookPath(bin); err != nil {
		return "", fmt.Errorf("%q not on PATH: %w", bin, err)
	}

	args := []string{"-p"}
	if c.Model != "" {
		args = append(args, "--model", c.Model)
	}
	args = append(args, c.ExtraArgs...)
	args = append(args, systemPrompt)

	cmd := exec.CommandContext(ctx, bin, args...)
	cmd.Stdin = strings.NewReader(userContent)
	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr
	if err := cmd.Run(); err != nil {
		return "", fmt.Errorf("%s: %w (stderr: %s)", bin, err, strings.TrimSpace(stderr.String()))
	}
	return strings.TrimSpace(stdout.String()), nil
}