package tui

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

    "ai-agent/internal/llm"

    tea "charm.land/bubbletea/v2"
)

func runCommit(client llm.Client, model string, extraMsg string) tea.Cmd {
    return func() tea.Msg {
        diff, err := gitDiff()
        if err != nil {
            return CommitResultMsg{Err: fmt.Errorf("git diff: %w", err)}
        }
        if strings.TrimSpace(diff) == "" {
            return CommitResultMsg{Err: fmt.Errorf("no staged changes (use `git add` first)")}
        }
        if len(diff) > 8000 {
            diff = diff[:8000] + "\n... (truncated)"
        }
        prompt := "Write a concise git commit message for the following staged diff. " +
            "Return ONLY the commit message, no explanation or markdown. " +
            "Use conventional commit style (e.g. feat:, fix:, refactor:). " +
            "Keep the first line under 72 characters."
        if extraMsg != "" {
            prompt += "\n\nAdditional context: " + extraMsg
        }
        prompt += "\n\nDiff:\n" + diff
        var msgBuf strings.Builder
        err = client.ChatStream(context.Background(), llm.ChatOptions{
            Messages: []llm.Message{{Role: "user", Content: prompt}},
            System:   "You are a helpful assistant that writes git commit messages.",
        }, func(chunk llm.StreamChunk) error {
            if chunk.Text != "" {
                msgBuf.WriteString(chunk.Text)
            }
            return nil
        })
        if err != nil {
            return CommitResultMsg{Err: fmt.Errorf("LLM error: %w", err)}
        }
        commitMsg := strings.TrimSpace(msgBuf.String())
        if commitMsg == "" {
            return CommitResultMsg{Err: fmt.Errorf("LLM returned empty commit message")}
        }
        commitMsg += fmt.Sprintf("\n\nAssisted-by: ai-agent (%s)", model)
        if err := gitCommit(commitMsg); err != nil {
            return CommitResultMsg{Err: fmt.Errorf("git commit: %w", err)}
        }
        return CommitResultMsg{Message: commitMsg}
    }
}

func gitDiff() (string, error) {
    cmd := exec.Command("git", "diff", "--cached", "--stat")
    stat, _ := cmd.Output()
    cmd = exec.Command("git", "diff", "--cached")
    out, err := cmd.Output()
    if err != nil {
        return "", err
    }
    return string(stat) + "\n" + string(out), nil
}

func gitCommit(msg string) error {
    cmd := exec.Command("git", "commit", "-m", msg)
    var stderr bytes.Buffer
    cmd.Stderr = &stderr
    if err := cmd.Run(); err != nil {
        return fmt.Errorf("%s: %s", err, stderr.String())
    }
    return nil
}