package agents

import (
	"context"
	"fmt"
	"strings"

	"g.fc.run/ai/byre/internal/api"
	"g.fc.run/ai/byre/internal/git"
)

func (m *Manager) prepareMainCommit(ctx context.Context, task api.Task, project api.Project, user api.User) (string, string, error) {
	coAuthors, err := m.CoAuthors(ctx, task.Id, user.Login)
	if err != nil {
		return "", "", err
	}
	env := git.IdentityEnv(user.GitName, user.GitEmail)
	commit, err := git.SquashCommit(project.RepoPath, task.WorktreePath, project.DefaultBranch, squashMessage(task.MergeTitle, coAuthors), env, m.signer(ctx, user))
	if err != nil || commit == "" {
		return "", "", err
	}
	note, err := m.mergeNote(ctx, task, user.Login)
	if err != nil {
		return "", "", err
	}
	notes, err := git.NoteCommit(project.RepoPath, commit, note, env)
	return commit, notes, err
}

func advanceMainCheckout(project api.Project, commit, notes string) error {
	pushed := git.Remote + "/" + project.DefaultBranch
	err := git.AdvanceNotes(project.RepoPath, notes)
	if err != nil {
		return fmt.Errorf("pushed %s to %s, but updating %s in the project checkout failed: %w", commit, pushed, git.NotesRef, err)
	}
	err = git.FastForward(project.RepoPath, commit)
	if err != nil {
		return fmt.Errorf("pushed %s to %s, but fast-forwarding the project checkout failed: %w", commit, pushed, err)
	}
	return nil
}

func (m *Manager) CoAuthors(ctx context.Context, taskID, login string) ([]api.Participant, error) {
	participants, err := m.store.Participants(ctx, taskID)
	if err != nil {
		return nil, err
	}

	coAuthors := []api.Participant{}
	for _, p := range participants {
		if p.Login != login {
			coAuthors = append(coAuthors, p)
		}
	}
	return coAuthors, nil
}

func squashMessage(title string, coAuthors []api.Participant) string {
	trailers := []string{}
	for _, p := range coAuthors {
		if p.GitName == "" || p.GitEmail == "" {
			continue
		}
		trailers = append(trailers, fmt.Sprintf("Co-authored-by: %s <%s>", p.GitName, p.GitEmail))
	}
	if len(trailers) == 0 {
		return title
	}
	return title + "\n\n" + strings.Join(trailers, "\n")
}