// Copyright 2023 Harness, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package pullreq

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/harness/gitness/app/api/usererror"
	"github.com/harness/gitness/app/auth"
	"github.com/harness/gitness/gitrpc"
	"github.com/harness/gitness/store"
	"github.com/harness/gitness/store/database/dbtx"
	"github.com/harness/gitness/types"
	"github.com/harness/gitness/types/enum"

	"github.com/rs/zerolog/log"
)

type ReviewSubmitInput struct {
	CommitSHA string                     `json:"commit_sha"`
	Decision  enum.PullReqReviewDecision `json:"decision"`
	Message   string                     `json:"message"`
}

func (in *ReviewSubmitInput) Validate() error {
	if in.CommitSHA == "" {
		return usererror.BadRequest("CommitSHA is a mandatory field")
	}

	decision, ok := in.Decision.Sanitize()
	if !ok || decision == enum.PullReqReviewDecisionPending {
		msg := fmt.Sprintf("Decision must be: %q, %q or %q.",
			enum.PullReqReviewDecisionApproved,
			enum.PullReqReviewDecisionChangeReq,
			enum.PullReqReviewDecisionReviewed)
		return usererror.BadRequest(msg)
	}

	in.Decision = decision
	in.Message = strings.TrimSpace(in.Message)

	// TODO: Check the length of the message string

	return nil
}

// ReviewSubmit creates a new pull request review.
func (c *Controller) ReviewSubmit(
	ctx context.Context,
	session *auth.Session,
	repoRef string,
	prNum int64,
	in *ReviewSubmitInput,
) (*types.PullReqReview, error) {
	if err := in.Validate(); err != nil {
		return nil, err
	}

	repo, err := c.getRepoCheckAccess(ctx, session, repoRef, enum.PermissionRepoView)
	if err != nil {
		return nil, fmt.Errorf("failed to acquire access to repo: %w", err)
	}

	pr, err := c.pullreqStore.FindByNumber(ctx, repo.ID, prNum)
	if err != nil {
		return nil, fmt.Errorf("failed to find pull request by number: %w", err)
	}

	if pr.CreatedBy == session.Principal.ID {
		return nil, usererror.BadRequest("Can't submit review to own pull requests.")
	}

	commit, err := c.gitRPCClient.GetCommit(ctx, &gitrpc.GetCommitParams{
		ReadParams: gitrpc.ReadParams{RepoUID: repo.GitUID},
		SHA:        in.CommitSHA,
	})
	if err != nil {
		return nil, fmt.Errorf("failed to get git branch sha: %w", err)
	}

	commitSHA := commit.Commit.SHA

	var review *types.PullReqReview

	err = dbtx.New(c.db).WithTx(ctx, func(ctx context.Context) error {
		now := time.Now().UnixMilli()
		review = &types.PullReqReview{
			ID:        0,
			CreatedBy: session.Principal.ID,
			Created:   now,
			Updated:   now,
			PullReqID: pr.ID,
			Decision:  in.Decision,
			SHA:       commitSHA,
		}

		err = c.reviewStore.Create(ctx, review)
		if err != nil {
			return err
		}

		_, err = c.updateReviewer(ctx, session, pr, review, commitSHA)
		return err
	})
	if err != nil {
		return nil, err
	}

	err = func() error {
		if pr, err = c.pullreqStore.UpdateActivitySeq(ctx, pr); err != nil {
			return fmt.Errorf("failed to increment pull request activity sequence: %w", err)
		}

		payload := &types.PullRequestActivityPayloadReviewSubmit{
			CommitSHA: commitSHA,
			Message:   in.Message,
			Decision:  in.Decision,
		}
		_, err = c.activityStore.CreateWithPayload(ctx, pr, session.Principal.ID, payload)
		return err
	}()
	if err != nil {
		// non-critical error
		log.Ctx(ctx).Err(err).Msgf("failed to write pull request activity after review submit")
	}

	return review, nil
}

// updateReviewer updates pull request reviewer object.
func (c *Controller) updateReviewer(ctx context.Context, session *auth.Session,
	pr *types.PullReq, review *types.PullReqReview, sha string) (*types.PullReqReviewer, error) {
	reviewer, err := c.reviewerStore.Find(ctx, pr.ID, session.Principal.ID)
	if err != nil && !errors.Is(err, store.ErrResourceNotFound) {
		return nil, err
	}

	if reviewer != nil {
		reviewer.LatestReviewID = &review.ID
		reviewer.ReviewDecision = review.Decision
		reviewer.SHA = sha
		err = c.reviewerStore.Update(ctx, reviewer)
	} else {
		now := time.Now().UnixMilli()
		reviewer = &types.PullReqReviewer{
			PullReqID:      pr.ID,
			PrincipalID:    session.Principal.ID,
			CreatedBy:      session.Principal.ID,
			Created:        now,
			Updated:        now,
			RepoID:         pr.TargetRepoID,
			Type:           enum.PullReqReviewerTypeSelfAssigned,
			LatestReviewID: &review.ID,
			ReviewDecision: review.Decision,
			SHA:            sha,
			Reviewer:       types.PrincipalInfo{},
			AddedBy:        types.PrincipalInfo{},
		}
		err = c.reviewerStore.Create(ctx, reviewer)
	}
	if err != nil {
		return nil, fmt.Errorf("failed to create/update reviewer")
	}

	return reviewer, nil
}