package supervisor

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

// RunResult holds the outcome of running a task via an external command.
type RunResult struct {
	TaskID     string
	StartedAt  time.Time
	FinishedAt time.Time
	Duration   time.Duration
	ExitCode   int
	Output     string // stdout
	Error      string // stderr
}

// CommandBuilder defines how to build the command for running a task.
// This allows tests to substitute mock commands.
type CommandBuilder func(ctx context.Context, task Task, projectPath string) *exec.Cmd

// DefaultCommandBuilder creates the command to run Claude Code CLI.
func DefaultCommandBuilder(ctx context.Context, task Task, projectPath string) *exec.Cmd {
	prompt := buildPrompt(task)
	model := strings.ToLower(task.Model)

	cmd := exec.CommandContext(ctx, "claude",
		"--print",
		"--model", model,
		"--message", prompt,
	)
	cmd.Dir = projectPath
	return cmd
}

// RunTask executes a task using the given command builder, with timeout support.
// If cmdBuilder is nil, DefaultCommandBuilder is used.
func RunTask(task Task, projectPath string, timeout time.Duration, cmdBuilder CommandBuilder) RunResult {
	result := RunResult{
		TaskID: task.ID,
	}

	if task.ID == "" {
		result.ExitCode = 1
		result.Error = "empty task ID"
		return result
	}

	if cmdBuilder == nil {
		cmdBuilder = DefaultCommandBuilder
	}

	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()

	cmd := cmdBuilder(ctx, task, projectPath)

	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr

	result.StartedAt = time.Now()
	err := cmd.Run()
	result.FinishedAt = time.Now()
	result.Duration = result.FinishedAt.Sub(result.StartedAt)
	result.Output = stdout.String()
	result.Error = stderr.String()

	if err != nil {
		if exitErr, ok := err.(*exec.ExitError); ok {
			result.ExitCode = exitErr.ExitCode()
		} else {
			result.ExitCode = 1
			if result.Error == "" {
				result.Error = err.Error()
			}
		}
	}

	return result
}

// buildPrompt creates the prompt string to send to Claude Code.
func buildPrompt(task Task) string {
	return fmt.Sprintf(`Radi na KAOS projektu.
Tvoj task: %s — %s
Pročitaj CLAUDE.md u root-u projekta za pravila rada.
%s
Kad završiš: go build, go test, commituj sa "T%s: opis".`,
		task.ID, task.Title, task.Description, task.ID[1:])
}