// 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 repo

import (
	"context"
	"io"
	"strings"

	"github.com/harness/gitness/gitrpc"
	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/config"
	"github.com/harness/gitness/types"
	"github.com/harness/gitness/types/enum"
)

func (c *Controller) RawDiff(
	ctx context.Context,
	session *auth.Session,
	repoRef string,
	path string,
	w io.Writer,
) error {
	repo, err := c.repoStore.FindByRef(ctx, repoRef)
	if err != nil {
		return err
	}

	if err = apiauth.CheckRepo(ctx, c.authorizer, session, repo, enum.PermissionRepoView, false); err != nil {
		return err
	}

	info, err := parseDiffPath(path)
	if err != nil {
		return err
	}

	return c.gitRPCClient.RawDiff(ctx, &gitrpc.DiffParams{
		ReadParams: CreateRPCReadParams(repo),
		BaseRef:    info.BaseRef,
		HeadRef:    info.HeadRef,
		MergeBase:  info.MergeBase,
	}, w)
}

type CompareInfo struct {
	BaseRef   string
	HeadRef   string
	MergeBase bool
}

func parseDiffPath(path string) (CompareInfo, error) {
	infos := strings.SplitN(path, "...", 2)
	if len(infos) != 2 {
		infos = strings.SplitN(path, "..", 2)
	}
	if len(infos) != 2 {
		return CompareInfo{}, usererror.BadRequestf("invalid format \"%s\"", path)
	}
	return CompareInfo{
		BaseRef:   infos[0],
		HeadRef:   infos[1],
		MergeBase: strings.Contains(path, "..."),
	}, nil
}

func (c *Controller) DiffStats(
	ctx context.Context,
	session *auth.Session,
	repoRef string,
	path string,
) (types.DiffStats, error) {
	repo, err := c.repoStore.FindByRef(ctx, repoRef)
	if err != nil {
		return types.DiffStats{}, err
	}

	if err = apiauth.CheckRepo(ctx, c.authorizer, session, repo, enum.PermissionRepoView, false); err != nil {
		return types.DiffStats{}, err
	}

	info, err := parseDiffPath(path)
	if err != nil {
		return types.DiffStats{}, err
	}

	output, err := c.gitRPCClient.DiffStats(ctx, &gitrpc.DiffParams{
		ReadParams: gitrpc.CreateRPCReadParams(repo),
		BaseRef:    info.BaseRef,
		HeadRef:    info.HeadRef,
	})
	if err != nil {
		return types.DiffStats{}, err
	}

	return types.DiffStats{
		Commits:      output.Commits,
		FilesChanged: output.FilesChanged,
	}, nil
}

func (c *Controller) Diff(
	ctx context.Context,
	session *auth.Session,
	repoRef string,
	path string,
	includePatch bool,
) (types.Stream[*gitrpc.FileDiff], error) {
	repo, err := c.repoStore.FindByRef(ctx, repoRef)
	if err != nil {
		return nil, err
	}

	if err = apiauth.CheckRepo(ctx, c.authorizer, session, repo, enum.PermissionRepoView, false); err != nil {
		return nil, err
	}

	info, err := parseDiffPath(path)
	if err != nil {
		return nil, err
	}

	reader := gitrpc.NewStreamReader(c.gitRPCClient.Diff(ctx, &gitrpc.DiffParams{
		ReadParams:   gitrpc.CreateRPCReadParams(repo),
		BaseRef:      info.BaseRef,
		HeadRef:      info.HeadRef,
		MergeBase:    info.MergeBase,
		IncludePatch: includePatch,
	}, config.ApiURL))

	return reader, nil
}