gitea-tea/internal/services/pulls.go

// Copyright 2026 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package services

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	gitea "gitea.dev/sdk"
	"gitea.dev/tea/internal/transport"
)

// Pull is the stable command representation of a pull request.
type Pull struct {
	Author            string          `json:"author"`
	CreatedAt         string          `json:"created_at"`
	UpdatedAt         string          `json:"updated_at"`
	Assignees         []string        `json:"assignees"`
	Milestone         *IssueMilestone `json:"milestone"`
	Labels            []Label         `json:"labels"`
	Deadline          *string         `json:"due_date"`
	ID                int64           `json:"id"`
	Number            int64           `json:"number"`
	Title             string          `json:"title"`
	Body              string          `json:"body"`
	URL               string          `json:"url"`
	State             string          `json:"state"`
	Merged            bool            `json:"merged"`
	Mergeable         bool            `json:"mergeable"`
	Draft             bool            `json:"-"`
	Base              string          `json:"base"`
	Head              string          `json:"head"`
	HeadSHA           string          `json:"head_sha"`
	HeadRepo          string          `json:"head_repo,omitempty"`
	HeadRemoteDeleted bool            `json:"head_remote_deleted"`
	HeadCanPush       bool            `json:"-"`
	HeadCloneURL      string          `json:"-"`
	HeadSSHURL        string          `json:"-"`
	Reviewers         []string        `json:"reviewers"`
	ReviewerTeams     []string        `json:"reviewer_teams"`
	Comments          int64           `json:"comments"`
}

func pullHeadBranch(number int64, ref, label string) (branch string, deleted bool) {
	if ref == fmt.Sprintf("refs/pull/%d/head", number) {
		branch = label
		if _, name, ok := strings.Cut(label, ":"); ok && name != "" {
			branch = name
		}
		return branch, true
	}
	return ref, false
}

func pullFrom(pull *gitea.PullRequest) Pull {
	var head, base gitea.PRBranchInfo
	if pull.Head != nil {
		head = *pull.Head
	}
	if pull.Base != nil {
		base = *pull.Base
	}
	headBranch, remoteDeleted := pullHeadBranch(pull.Index, head.Ref, head.Name)
	result := Pull{
		Author: login(pull.Poster), CreatedAt: timestamp(deref(pull.Created)), UpdatedAt: timestamp(deref(pull.Updated)),
		Assignees: convertAll(pull.Assignees, login), Milestone: issueMilestoneFrom(pull.Milestone), Labels: convertAll(pull.Labels, labelFrom),
		Deadline: optionalTimestamp(pull.Deadline), ID: pull.ID, Number: pull.Index, Title: pull.Title, Body: pull.Body,
		URL: pull.HTMLURL, State: string(pull.State), Merged: pull.HasMerged, Mergeable: pull.Mergeable, Draft: pull.Draft,
		Base: base.Ref, Head: headBranch, HeadSHA: head.Sha, HeadRemoteDeleted: remoteDeleted,
		Reviewers: convertAll(pull.RequestedReviewers, login), Comments: int64(pull.Comments),
		ReviewerTeams: convertAll(pull.RequestedReviewersTeams, func(team *gitea.Team) string { return team.Name }),
	}
	repo := head.Repository
	if remoteDeleted || repo == nil {
		repo = base.Repository
	}
	if repo != nil {
		result.HeadRepo, result.HeadCloneURL, result.HeadSSHURL = repo.FullName, repo.CloneURL, repo.SSHURL
		if repo.Permissions != nil {
			result.HeadCanPush = repo.Permissions.Push
		}
	}
	return result
}

// PullOptions supplies validated branch and content input for creation.
type PullOptions struct {
	Assignees           []string   `json:"assignees,omitempty"`
	Labels              []int64    `json:"labels,omitempty"`
	Milestone           int64      `json:"milestone,omitempty"`
	Deadline            *time.Time `json:"due_date,omitempty"`
	Title               string     `json:"title"`
	Body                string     `json:"body"`
	Base                string     `json:"base"`
	Head                string     `json:"head"`
	AllowMaintainerEdit *bool      `json:"allow_maintainer_edit,omitempty"`
}

// PullEdit distinguishes omitted fields from explicit empty values.
type PullEdit struct {
	Labels              *[]int64              `json:"-"`
	Title               *string               `json:"title,omitempty"`
	Body                *string               `json:"body,omitempty"`
	State               *string               `json:"state,omitempty"`
	Base                *string               `json:"base,omitempty"`
	AllowMaintainerEdit *bool                 `json:"allow_maintainer_edit,omitempty"`
	Assignees           *[]string             `json:"assignees,omitempty"`
	Milestone           *int64                `json:"-"`
	ReviewerChanges     *ReviewRequestChanges `json:"-"`
	Deadline            *time.Time            `json:"due_date,omitempty"`
	RemoveDeadline      *bool                 `json:"unset_due_date,omitempty"`
	Changes             *MetadataChanges      `json:"-"`
}

// Pulls implements repository pull request operations.
type Pulls struct {
	Client     *transport.Client
	Repository string
}

// PullListOptions supplies server-supported pull request filters.
type PullListOptions struct {
	State, Sort, Author, Base string
	Limit, Page               int
	Milestone                 int64
	Labels                    []int64
}

// List returns a page of pull requests, even when the server caps its page size below the
// limit, and reports whether more pull requests follow.
func (s Pulls) List(ctx context.Context, options PullListOptions) ([]Pull, bool, error) {
	query := url.Values{"state": {options.State}}
	if options.Sort != "" {
		query.Set("sort", options.Sort)
	}
	if options.Author != "" {
		query.Set("poster", options.Author)
	}
	if options.Base != "" {
		query.Set("base_branch", options.Base)
	}
	if options.Milestone > 0 {
		query.Set("milestone", strconv.FormatInt(options.Milestone, 10))
	}
	for _, label := range options.Labels {
		query.Add("labels", strconv.FormatInt(label, 10))
	}

	// TODO(sdk): ListPullRequestsOptions lacks the poster, base_branch, and labels filters.
	pulls, more, err := rawWindow[*gitea.PullRequest](ctx, s.Client, "repos/"+s.Repository+"/pulls", query, options.Limit, options.Page)
	if err != nil {
		return nil, false, err
	}
	return convertAll(pulls, pullFrom), more, nil
}

// View retrieves one pull request.
func (s Pulls) View(ctx context.Context, n int64) (Pull, error) {
	pull, err := s.get(ctx, n)
	if err != nil {
		return Pull{}, err
	}
	return pullFrom(pull), nil
}

func (s Pulls) get(ctx context.Context, n int64) (*gitea.PullRequest, error) {
	return repoCall(ctx, s.Client, s.Repository, func(ctx context.Context, c *gitea.Client, owner, name string) (*gitea.PullRequest, *gitea.Response, error) {
		return c.PullRequests.GetPullRequest(ctx, owner, name, n)
	})
}

// ListOpen returns every open pull request in the repository.
func (s Pulls) ListOpen(ctx context.Context) ([]Pull, error) {
	return listAll(func(page int) ([]Pull, error) {
		items, _, err := s.List(ctx, PullListOptions{State: "open", Limit: 50, Page: page})
		return items, err
	})
}

// FindOpenByHead returns the unique open pull whose head branch matches name.
func (s Pulls) FindOpenByHead(ctx context.Context, head string) (Pull, error) {
	head = strings.TrimSpace(head)
	if head == "" {
		return Pull{}, fmt.Errorf("head branch cannot be empty")
	}
	items, err := s.ListOpen(ctx)
	if err != nil {
		return Pull{}, err
	}
	matches := []Pull{}
	for _, item := range items {
		if item.Head == head {
			matches = append(matches, item)
		}
	}
	switch len(matches) {
	case 0:
		return Pull{}, fmt.Errorf("no open pull request uses head branch %q", head)
	case 1:
		return matches[0], nil
	default:
		return Pull{}, fmt.Errorf("multiple open pull requests use head branch %q; supply an explicit number", head)
	}
}

// Create opens a pull request.
func (s Pulls) Create(ctx context.Context, opts PullOptions) (Pull, error) {
	// TODO(sdk): CreatePullRequestOption lacks allow_maintainer_edit.
	var pull gitea.PullRequest
	if err := sendJSON(ctx, s.Client, http.MethodPost, "repos/"+s.Repository+"/pulls", opts, &pull); err != nil {
		return Pull{}, err
	}
	return pullFrom(&pull), nil
}

// Edit updates only explicitly supplied resource fields.
func (s Pulls) Edit(ctx context.Context, n int64, opts PullEdit) (Pull, error) {
	if opts.ReviewerChanges != nil {
		item, err := (Reviews{Client: s.Client, Repository: s.Repository}).ChangeRequests(ctx, n, *opts.ReviewerChanges)
		if err != nil {
			return Pull{}, err
		}
		opts.ReviewerChanges = nil
		if opts == (PullEdit{}) {
			return item, nil
		}
		item, err = s.Edit(ctx, n, opts)
		if err != nil {
			return Pull{}, fmt.Errorf("review requests were updated, but editing other pull request fields failed: %w", err)
		}
		return item, nil
	}
	issues := Issues{Client: s.Client, Repository: s.Repository}
	if opts.Changes != nil {
		resolved, err := issues.applyChanges(ctx, n, IssueEdit{Labels: opts.Labels, Assignees: opts.Assignees, Changes: opts.Changes})
		if err != nil {
			return Pull{}, err
		}
		opts.Labels, opts.Assignees, opts.Changes = resolved.Labels, resolved.Assignees, nil
	}
	if opts.Milestone != nil || opts.Labels != nil {
		// The PR endpoint ignores zero milestones. Its issue endpoint supports
		// clearing and lets common fields share the same mutation.
		_, err := issues.Edit(ctx, n, IssueEdit{
			Title: opts.Title, Body: opts.Body, Assignees: opts.Assignees, Milestone: opts.Milestone, Labels: opts.Labels,
			Deadline: opts.Deadline, RemoveDeadline: opts.RemoveDeadline,
		})
		if err != nil {
			return Pull{}, err
		}
		opts.Title, opts.Body, opts.Assignees, opts.Milestone = nil, nil, nil, nil
		opts.Deadline, opts.RemoveDeadline, opts.Labels = nil, nil, nil
		var result Pull
		if opts == (PullEdit{}) {
			result, err = s.View(ctx, n)
		} else {
			result, err = s.Edit(ctx, n, opts)
		}
		if err != nil {
			return Pull{}, fmt.Errorf("issue fields were updated, but completing the pull request edit failed: %w", err)
		}
		return result, nil
	}
	return repoConvert(ctx, s.Client, s.Repository, pullFrom, func(ctx context.Context, c *gitea.Client, owner, name string) (*gitea.PullRequest, *gitea.Response, error) {
		return c.PullRequests.EditPullRequest(ctx, owner, name, n, editPullOption(opts))
	})
}

func editPullOption(opts PullEdit) gitea.EditPullRequestOption {
	option := gitea.EditPullRequestOption{
		Body: opts.Body, Deadline: opts.Deadline, RemoveDeadline: opts.RemoveDeadline, AllowMaintainerEdit: opts.AllowMaintainerEdit,
	}
	if opts.Title != nil {
		option.Title = *opts.Title
	}
	if opts.Base != nil {
		option.Base = *opts.Base
	}
	if opts.Assignees != nil {
		option.Assignees = *opts.Assignees
	}
	if opts.State != nil {
		state := gitea.StateType(*opts.State)
		option.State = &state
	}
	return option
}

// Diff returns the pull request's patch, which the caller must close.
func (s Pulls) Diff(ctx context.Context, n int64) (io.ReadCloser, error) {
	diff, err := repoCall(ctx, s.Client, s.Repository, func(ctx context.Context, c *gitea.Client, owner, name string) ([]byte, *gitea.Response, error) {
		return c.PullRequests.GetPullRequestDiff(ctx, owner, name, n, gitea.PullRequestDiffOptions{})
	})
	if err != nil {
		return nil, err
	}
	return io.NopCloser(bytes.NewReader(diff)), nil
}

// MergeOptions supplies merge strategy and optional commit text.
type MergeOptions struct {
	Method, Title, Message string
	DeleteBranch           bool
}

// Merge merges the pull request's current head with the selected strategy; Gitea refuses the
// merge if the head moves meanwhile. When Gitea refuses the merge, the error names the reason
// derived from the pull request, since Gitea reports conflicts only as "try again later".
func (s Pulls) Merge(ctx context.Context, n int64, opts MergeOptions) error {
	pull, err := s.get(ctx, n)
	if err != nil {
		return err
	}
	option := gitea.MergePullRequestOption{
		Style: gitea.MergeStyle(opts.Method), Title: opts.Title, Message: opts.Message, DeleteBranchAfterMerge: &opts.DeleteBranch,
	}
	if pull.Head != nil {
		option.HeadCommitId = pull.Head.Sha
	}
	err = repoDo(ctx, s.Client, s.Repository, func(ctx context.Context, c *gitea.Client, owner, name string) (*gitea.Response, error) {
		_, resp, err := c.PullRequests.MergePullRequest(ctx, owner, name, n, option)
		return resp, err
	})
	if refused, ok := errors.AsType[*transport.APIError](err); !ok || refused.Status != http.StatusMethodNotAllowed {
		return err
	}
	var reason string
	switch {
	case pull.HasMerged:
		reason = "has already been merged"
	case pull.State == gitea.StateClosed:
		reason = "is closed"
	case pull.Draft:
		reason = "is a draft; mark it ready for review first"
	case !pull.Mergeable:
		reason = "has conflicting files or is otherwise not mergeable"
	default:
		return err
	}
	return fmt.Errorf("pull request #%d %s: %w", n, reason, err)
}

// pullTemplatePaths lists the Markdown pull request templates Gitea reads, in its priority order.
var pullTemplatePaths = []string{
	"PULL_REQUEST_TEMPLATE.md", "pull_request_template.md",
	".gitea/PULL_REQUEST_TEMPLATE.md", ".gitea/pull_request_template.md",
	".github/PULL_REQUEST_TEMPLATE.md", ".github/pull_request_template.md",
}

const maxPullTemplateBytes = 1 << 20

// Template returns the first pull request template found at ref, or "" when the repository has none.
func (s Pulls) Template(ctx context.Context, ref string) (string, error) {
	for _, path := range pullTemplatePaths {
		file, err := repoCall(ctx, s.Client, s.Repository, func(ctx context.Context, c *gitea.Client, owner, name string) (io.ReadCloser, *gitea.Response, error) {
			return c.Repositories.GetFileReader(ctx, owner, name, ref, path)
		})
		if err != nil {
			if apiError, ok := errors.AsType[*transport.APIError](err); ok && apiError.Status == http.StatusNotFound {
				continue
			}
			return "", err
		}
		data, err := io.ReadAll(io.LimitReader(file, maxPullTemplateBytes))
		_ = file.Close()
		return string(data), err
	}
	return "", nil
}