package cmd

import (
	"fmt"
	"strings"

	"github.com/fatih/color"
	"github.com/spf13/cobra"
	"gmgauthier.com/grokkit/config"
	"gmgauthier.com/grokkit/internal/git"
)

// gitDiff is the mockable entry point (exactly like gitRun used elsewhere).
var gitDiff = git.Diff

var prDescribeCmd = &cobra.Command{
	Use:   "pr-describe",
	Short: "Generate full PR description from current branch",
	Run:   runPRDescribe,
}

func init() {
	prDescribeCmd.Flags().StringP("base", "b", "master", "Base branch to compare against (default: master)")
}

func runPRDescribe(cmd *cobra.Command, _ []string) {
	base, _ := cmd.Flags().GetString("base")

	// Prefer remote (more likely up-to-date for PRs), fallback to local.
	diff, err := gitDiff([]string{"diff", fmt.Sprintf("origin/%s..HEAD", base), "--no-color"})
	if err != nil || strings.TrimSpace(diff) == "" {
		diff, err = gitDiff([]string{"diff", fmt.Sprintf("%s..HEAD", base), "--no-color"})
		if err != nil {
			color.Red("Failed to get branch diff: %v", err)
			return
		}
	}
	if strings.TrimSpace(diff) == "" {
		color.Yellow("No changes on this branch compared to %s/origin/%s.", base, base)
		return
	}

	modelFlag, _ := cmd.Flags().GetString("model")
	model := config.GetModel("prdescribe", modelFlag)

	client := newGrokClient()
	messages := buildPRDescribeMessages(diff)
	color.Yellow("Writing PR description (base=%s)...", base)
	client.Stream(messages, model)
}

func buildPRDescribeMessages(diff string) []map[string]string {
	return []map[string]string{
		{"role": "system", "content": "Write a professional GitHub PR title + detailed body (changes, motivation, testing notes)."},
		{"role": "user", "content": fmt.Sprintf("Diff:\n%s", diff)},
	}
}