// Copyright 2022 Harness Inc. All rights reserved.
// Use of this source code is governed by the Polyform Free Trial License
// that can be found in the LICENSE.md file for this repository.

package pullreq

import (
	"context"
	"errors"
	"fmt"

	"github.com/harness/gitness/gitrpc"
	gitrpcenum "github.com/harness/gitness/gitrpc/enum"
	apiauth "github.com/harness/gitness/internal/api/auth"
	"github.com/harness/gitness/internal/api/usererror"
	"github.com/harness/gitness/internal/auth"
	"github.com/harness/gitness/internal/auth/authz"
	pullreqevents "github.com/harness/gitness/internal/events/pullreq"
	"github.com/harness/gitness/internal/store"
	"github.com/harness/gitness/internal/url"
	"github.com/harness/gitness/lock"
	"github.com/harness/gitness/types"
	"github.com/harness/gitness/types/enum"

	"github.com/jmoiron/sqlx"
)

type Controller struct {
	db             *sqlx.DB
	urlProvider    *url.Provider
	authorizer     authz.Authorizer
	pullreqStore   store.PullReqStore
	activityStore  store.PullReqActivityStore
	reviewStore    store.PullReqReviewStore
	reviewerStore  store.PullReqReviewerStore
	repoStore      store.RepoStore
	principalStore store.PrincipalStore
	gitRPCClient   gitrpc.Interface
	eventReporter  *pullreqevents.Reporter
	mtxManager     lock.MutexManager
}

func NewController(
	db *sqlx.DB,
	urlProvider *url.Provider,
	authorizer authz.Authorizer,
	pullreqStore store.PullReqStore,
	pullreqActivityStore store.PullReqActivityStore,
	pullreqReviewStore store.PullReqReviewStore,
	pullreqReviewerStore store.PullReqReviewerStore,
	repoStore store.RepoStore,
	principalStore store.PrincipalStore,
	gitRPCClient gitrpc.Interface,
	eventReporter *pullreqevents.Reporter,
	mtxManager lock.MutexManager,
) *Controller {
	return &Controller{
		db:             db,
		urlProvider:    urlProvider,
		authorizer:     authorizer,
		pullreqStore:   pullreqStore,
		activityStore:  pullreqActivityStore,
		reviewStore:    pullreqReviewStore,
		reviewerStore:  pullreqReviewerStore,
		repoStore:      repoStore,
		principalStore: principalStore,
		gitRPCClient:   gitRPCClient,
		eventReporter:  eventReporter,
		mtxManager:     mtxManager,
	}
}

func (c *Controller) verifyBranchExistence(ctx context.Context,
	repo *types.Repository, branch string,
) (string, error) {
	if branch == "" {
		return "", usererror.BadRequest("branch name can't be empty")
	}

	ref, err := c.gitRPCClient.GetRef(ctx,
		gitrpc.GetRefParams{
			ReadParams: gitrpc.ReadParams{RepoUID: repo.GitUID},
			Name:       branch,
			Type:       gitrpcenum.RefTypeBranch,
		})
	if errors.Is(err, gitrpc.ErrNotFound) {
		return "", usererror.BadRequest(
			fmt.Sprintf("branch %s does not exist in the repository %s", branch, repo.UID))
	}
	if err != nil {
		return "", fmt.Errorf(
			"failed to check existence of the branch %s in the repository %s: %w",
			branch, repo.UID, err)
	}

	return ref.SHA, nil
}

func (c *Controller) getRepoCheckAccess(ctx context.Context,
	session *auth.Session, repoRef string, reqPermission enum.Permission,
) (*types.Repository, error) {
	if repoRef == "" {
		return nil, usererror.BadRequest("A valid repository reference must be provided.")
	}

	repo, err := c.repoStore.FindByRef(ctx, repoRef)
	if err != nil {
		return nil, fmt.Errorf("failed to find repository: %w", err)
	}

	if err = apiauth.CheckRepo(ctx, c.authorizer, session, repo, reqPermission, false); err != nil {
		return nil, fmt.Errorf("access check failed: %w", err)
	}

	return repo, nil
}

func (c *Controller) getCommentCheckEditAccess(ctx context.Context,
	session *auth.Session, pr *types.PullReq, commentID int64,
) (*types.PullReqActivity, error) {
	if commentID <= 0 {
		return nil, usererror.BadRequest("A valid comment ID must be provided.")
	}

	comment, err := c.activityStore.Find(ctx, commentID)
	if err != nil {
		return nil, fmt.Errorf("failed to find comment by ID: %w", err)
	}

	if comment == nil || comment.Type != enum.PullReqActivityTypeComment {
		return nil, usererror.ErrNotFound
	}

	if comment.Deleted != nil || comment.RepoID != pr.TargetRepoID || comment.PullReqID != pr.ID {
		return nil, usererror.ErrNotFound
	}

	if comment.Kind == enum.PullReqActivityKindSystem {
		return nil, usererror.BadRequest("Can't update a comment created by the system.")
	}

	if comment.CreatedBy != session.Principal.ID {
		return nil, usererror.BadRequest("Only own comments may be updated.")
	}

	return comment, nil
}

// writeActivity updates the PR's activity sequence number (using the optimistic locking mechanism),
// sets the correct Order value and writes the activity to the database.
// Even if the writing fails, the updating of the sequence number can succeed.
func (c *Controller) writeActivity(ctx context.Context, pr *types.PullReq, act *types.PullReqActivity) error {
	prUpd, err := c.pullreqStore.UpdateActivitySeq(ctx, pr)
	if err != nil {
		return fmt.Errorf("failed to get pull request activity number: %w", err)
	}

	*pr = *prUpd // update the pull request object

	act.Order = prUpd.ActivitySeq

	err = c.activityStore.Create(ctx, act)
	if err != nil {
		return fmt.Errorf("failed to create pull request activity: %w", err)
	}

	return nil
}

// writeReplyActivity updates the parent activity's reply sequence number (using the optimistic locking mechanism),
// sets the correct Order and SubOrder values and writes the activity to the database.
// Even if the writing fails, the updating of the sequence number can succeed.
func (c *Controller) writeReplyActivity(ctx context.Context, parent, act *types.PullReqActivity) error {
	parentUpd, err := c.activityStore.UpdateReplySeq(ctx, parent)
	if err != nil {
		return fmt.Errorf("failed to get pull request activity number: %w", err)
	}

	*parent = *parentUpd // update the parent pull request activity object

	act.Order = parentUpd.Order
	act.SubOrder = parentUpd.ReplySeq

	err = c.activityStore.Create(ctx, act)
	if err != nil {
		return fmt.Errorf("failed to create pull request activity: %w", err)
	}

	return nil
}

func (c *Controller) checkIfAlreadyExists(ctx context.Context,
	targetRepoID, sourceRepoID int64, targetBranch, sourceBranch string,
) error {
	existing, err := c.pullreqStore.List(ctx, &types.PullReqFilter{
		SourceRepoID: sourceRepoID,
		SourceBranch: sourceBranch,
		TargetRepoID: targetRepoID,
		TargetBranch: targetBranch,
		States:       []enum.PullReqState{enum.PullReqStateOpen},
		Size:         1,
		Sort:         enum.PullReqSortNumber,
		Order:        enum.OrderAsc,
	})
	if err != nil {
		return fmt.Errorf("failed to get existing pull requests: %w", err)
	}
	if len(existing) > 0 {
		return usererror.BadRequestWithPayload(
			"a pull request for this target and source branch already exists",
			map[string]any{
				"type":   "pr already exists",
				"number": existing[0].Number,
			},
		)
	}

	return nil
}

func eventBase(pr *types.PullReq, targetRepo *types.Repository, principal *types.Principal) pullreqevents.Base {
	return pullreqevents.Base{
		PullReqID:        pr.ID,
		SourceRepoID:     pr.SourceRepoID,
		TargetRepoID:     pr.TargetRepoID,
		TargetRepoGitUID: targetRepo.GitUID,
		Number:           pr.Number,
		PrincipalID:      principal.ID,
	}
}