package main

// vcs.go defines the vcsClient interface that both gitea.Client (via giteaVCSAdapter)
// and github.Client (via githubVCSAdapter) satisfy, enabling VCS-type routing in main.go.
//
// Interface design:
//   - Methods cover all PR review operations used by main.go.
//   - Gitea-specific operations (supersede, comment resolution) are in the separate
//     giteaExtClient interface. GitHub implementations return ErrNotSupported for those.
//   - Types are defined here as package-local VCS types; each adapter converts from
//     its respective client package's types.

import (
	"context"
	"errors"

	"gitea.weiker.me/rodin/review-bot/gitea"
	"gitea.weiker.me/rodin/review-bot/github"
	"gitea.weiker.me/rodin/review-bot/review"
)

// ErrNotSupported is returned by VCS methods that have no implementation for
// a particular VCS backend (e.g., Gitea-specific timeline APIs on GitHub).
var ErrNotSupported = errors.New("operation not supported on this VCS backend")

// vcsClient is the interface for all PR operations used by main.go.
// It is implemented by both giteaVCSAdapter and githubVCSAdapter.
// Interface defined here (in the consumer package) per Go idiom.
type vcsClient interface {
	// PR metadata and content
	GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcsPullRequest, error)
	GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error)
	GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcsChangedFile, error)
	GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcsCommitStatus, error)
	GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error)
	GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error)
	ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error)
	GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error)

	// Review operations
	PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []vcsReviewComment) (*vcsReview, error)
	ListReviews(ctx context.Context, owner, repo string, number int) ([]vcsReview, error)
	DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error
	GetAuthenticatedUser(ctx context.Context) (string, error)
	RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error
}

// giteaExtClient extends vcsClient with Gitea-specific operations that have no
// GitHub equivalent. Code that uses these methods should first do a type assertion.
type giteaExtClient interface {
	vcsClient
	GetTimelineReviewCommentIDForReview(ctx context.Context, owner, repo string, prNum, reviewID int64) (int64, error)
	EditComment(ctx context.Context, owner, repo string, commentID int64, body string) error
	ListReviewComments(ctx context.Context, owner, repo string, prNum, reviewID int64) ([]gitea.ReviewComment, error)
	ResolveComment(ctx context.Context, owner, repo string, commentID int64) error
}

// --- shared VCS types ---

// vcsPullRequest is VCS-agnostic PR metadata.
type vcsPullRequest struct {
	Title string
	Body  string
	Head  struct {
		Sha string
		Ref string
	}
}

// vcsChangedFile is a file changed in a PR.
type vcsChangedFile struct {
	Filename string
	Status   string
}

// vcsCommitStatus is a CI status entry.
type vcsCommitStatus struct {
	Status      string
	Context     string
	Description string
	TargetURL   string
}

// vcsReviewComment is an inline review comment.
type vcsReviewComment struct {
	Path    string
	NewLine int64 // absolute line number on the new (right) side of the diff, used by both Gitea and GitHub adapters
	Body    string
}

// vcsReview is a submitted PR review.
type vcsReview struct {
	ID       int64
	Body     string
	CommitID string
	User     struct {
		Login string
	}
	State string
}

// ============================================================
// giteaVCSAdapter
// ============================================================

// giteaVCSAdapter wraps gitea.Client to implement vcsClient + giteaExtClient.
type giteaVCSAdapter struct {
	c *gitea.Client
}

func newGiteaVCSAdapter(c *gitea.Client) *giteaVCSAdapter { return &giteaVCSAdapter{c: c} }

func (a *giteaVCSAdapter) GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcsPullRequest, error) {
	pr, err := a.c.GetPullRequest(ctx, owner, repo, number)
	if err != nil {
		return nil, err
	}
	r := &vcsPullRequest{Title: pr.Title, Body: pr.Body}
	r.Head.Sha = pr.Head.Sha
	r.Head.Ref = pr.Head.Ref
	return r, nil
}

func (a *giteaVCSAdapter) GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error) {
	return a.c.GetPullRequestDiff(ctx, owner, repo, number)
}

func (a *giteaVCSAdapter) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcsChangedFile, error) {
	files, err := a.c.GetPullRequestFiles(ctx, owner, repo, number)
	if err != nil {
		return nil, err
	}
	out := make([]vcsChangedFile, len(files))
	for i, f := range files {
		out[i] = vcsChangedFile{Filename: f.Filename, Status: f.Status}
	}
	return out, nil
}

func (a *giteaVCSAdapter) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcsCommitStatus, error) {
	statuses, err := a.c.GetCommitStatuses(ctx, owner, repo, sha)
	if err != nil {
		return nil, err
	}
	out := make([]vcsCommitStatus, len(statuses))
	for i, s := range statuses {
		out[i] = vcsCommitStatus{Status: s.Status, Context: s.Context, Description: s.Description, TargetURL: s.TargetURL}
	}
	return out, nil
}

func (a *giteaVCSAdapter) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
	return a.c.GetFileContent(ctx, owner, repo, filepath)
}

func (a *giteaVCSAdapter) GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error) {
	return a.c.GetFileContentRef(ctx, owner, repo, filepath, ref)
}

func (a *giteaVCSAdapter) ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error) {
	entries, err := a.c.ListContents(ctx, owner, repo, path)
	if err != nil {
		return nil, err
	}
	out := make([]review.ContentEntry, len(entries))
	for i, e := range entries {
		out[i] = review.ContentEntry{Name: e.Name, Path: e.Path, Type: e.Type}
	}
	return out, nil
}

func (a *giteaVCSAdapter) GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error) {
	return a.c.GetAllFilesInPath(ctx, owner, repo, path)
}

func (a *giteaVCSAdapter) PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []vcsReviewComment) (*vcsReview, error) {
	gc := make([]gitea.ReviewComment, len(comments))
	for i, c := range comments {
		gc[i] = gitea.ReviewComment{Path: c.Path, NewPosition: c.NewLine, Body: c.Body}
	}
	r, err := a.c.PostReview(ctx, owner, repo, number, event, body, commitID, gc)
	if err != nil {
		return nil, err
	}
	out := &vcsReview{ID: r.ID, Body: r.Body, CommitID: r.CommitID, State: r.State}
	out.User.Login = r.User.Login
	return out, nil
}

func (a *giteaVCSAdapter) ListReviews(ctx context.Context, owner, repo string, number int) ([]vcsReview, error) {
	reviews, err := a.c.ListReviews(ctx, owner, repo, number)
	if err != nil {
		return nil, err
	}
	out := make([]vcsReview, len(reviews))
	for i, r := range reviews {
		out[i] = vcsReview{ID: r.ID, Body: r.Body, CommitID: r.CommitID, State: r.State}
		out[i].User.Login = r.User.Login
	}
	return out, nil
}

func (a *giteaVCSAdapter) DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error {
	return a.c.DeleteReview(ctx, owner, repo, number, reviewID)
}

func (a *giteaVCSAdapter) GetAuthenticatedUser(ctx context.Context) (string, error) {
	return a.c.GetAuthenticatedUser(ctx)
}

func (a *giteaVCSAdapter) RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error {
	return a.c.RequestReviewer(ctx, owner, repo, number, reviewer)
}

// Gitea-specific extension methods.

func (a *giteaVCSAdapter) GetTimelineReviewCommentIDForReview(ctx context.Context, owner, repo string, prNum, reviewID int64) (int64, error) {
	return a.c.GetTimelineReviewCommentIDForReview(ctx, owner, repo, int(prNum), reviewID)
}

func (a *giteaVCSAdapter) EditComment(ctx context.Context, owner, repo string, commentID int64, body string) error {
	return a.c.EditComment(ctx, owner, repo, commentID, body)
}

func (a *giteaVCSAdapter) ListReviewComments(ctx context.Context, owner, repo string, prNum, reviewID int64) ([]gitea.ReviewComment, error) {
	return a.c.ListReviewComments(ctx, owner, repo, int(prNum), reviewID)
}

func (a *giteaVCSAdapter) ResolveComment(ctx context.Context, owner, repo string, commentID int64) error {
	return a.c.ResolveComment(ctx, owner, repo, commentID)
}

// ============================================================
// githubVCSAdapter
// ============================================================

// githubVCSAdapter wraps github.Client to implement vcsClient.
// Gitea-specific extension methods (GetTimelineReviewCommentIDForReview, EditComment,
// ListReviewComments, ResolveComment) are not available on GitHub and will not be called
// because main.go gates them with a type assertion to giteaExtClient.
type githubVCSAdapter struct {
	c *github.Client
}

func newGithubVCSAdapter(c *github.Client) *githubVCSAdapter { return &githubVCSAdapter{c: c} }

func (a *githubVCSAdapter) GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcsPullRequest, error) {
	pr, err := a.c.GetPullRequest(ctx, owner, repo, number)
	if err != nil {
		return nil, err
	}
	r := &vcsPullRequest{Title: pr.Title, Body: pr.Body}
	r.Head.Sha = pr.Head.Sha
	r.Head.Ref = pr.Head.Ref
	return r, nil
}

func (a *githubVCSAdapter) GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error) {
	return a.c.GetPullRequestDiff(ctx, owner, repo, number)
}

func (a *githubVCSAdapter) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcsChangedFile, error) {
	files, err := a.c.GetPullRequestFiles(ctx, owner, repo, number)
	if err != nil {
		return nil, err
	}
	out := make([]vcsChangedFile, len(files))
	for i, f := range files {
		out[i] = vcsChangedFile{Filename: f.Filename, Status: f.Status}
	}
	return out, nil
}

func (a *githubVCSAdapter) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcsCommitStatus, error) {
	statuses, err := a.c.GetCommitStatuses(ctx, owner, repo, sha)
	if err != nil {
		return nil, err
	}
	out := make([]vcsCommitStatus, len(statuses))
	for i, s := range statuses {
		// CommitStatus.Status is tagged as json:"state" — already the normalized "state" value
		out[i] = vcsCommitStatus{Status: s.Status, Context: s.Context, Description: s.Description, TargetURL: s.TargetURL}
	}
	return out, nil
}

func (a *githubVCSAdapter) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
	return a.c.GetFileContent(ctx, owner, repo, filepath)
}

func (a *githubVCSAdapter) GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error) {
	return a.c.GetFileContentRef(ctx, owner, repo, filepath, ref)
}

func (a *githubVCSAdapter) ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error) {
	entries, err := a.c.ListContents(ctx, owner, repo, path)
	if err != nil {
		return nil, err
	}
	out := make([]review.ContentEntry, len(entries))
	for i, e := range entries {
		out[i] = review.ContentEntry{Name: e.Name, Path: e.Path, Type: e.Type}
	}
	return out, nil
}

func (a *githubVCSAdapter) GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error) {
	return a.c.GetAllFilesInPath(ctx, owner, repo, path)
}

func (a *githubVCSAdapter) PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []vcsReviewComment) (*vcsReview, error) {
	gc := make([]github.ReviewComment, len(comments))
	for i, c := range comments {
		// GitHub inline comments use Line+Side (absolute line on the RIGHT side).
		// NewLine from diff parsing gives absolute new-file line numbers.
		// Comments that cannot be mapped will be omitted (GitHub rejects invalid positions).
		gc[i] = github.ReviewComment{
			Path: c.Path,
			Line: c.NewLine,
			Side: "RIGHT",
			Body: c.Body,
		}
	}
	r, err := a.c.PostReview(ctx, owner, repo, number, event, body, commitID, gc)
	if err != nil {
		return nil, err
	}
	out := &vcsReview{ID: r.ID, Body: r.Body, State: r.State}
	out.User.Login = r.User.Login
	return out, nil
}

func (a *githubVCSAdapter) ListReviews(ctx context.Context, owner, repo string, number int) ([]vcsReview, error) {
	reviews, err := a.c.ListReviews(ctx, owner, repo, number)
	if err != nil {
		return nil, err
	}
	out := make([]vcsReview, len(reviews))
	for i, r := range reviews {
		out[i] = vcsReview{ID: r.ID, Body: r.Body, State: r.State}
		out[i].User.Login = r.User.Login
	}
	return out, nil
}

func (a *githubVCSAdapter) DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error {
	// GitHub only allows deleting PENDING (draft) reviews. review-bot posts submitted
	// reviews, so this will return an error for any review we actually posted.
	// Callers should treat 422 errors here gracefully.
	return a.c.DeleteReview(ctx, owner, repo, number, reviewID)
}

func (a *githubVCSAdapter) GetAuthenticatedUser(ctx context.Context) (string, error) {
	return a.c.GetAuthenticatedUser(ctx)
}

func (a *githubVCSAdapter) RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error {
	return a.c.RequestReviewer(ctx, owner, repo, number, reviewer)
}