// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package gitiles

import (
	"context"
	"fmt"
	"net/http"

	"go.chromium.org/luci/common/api/gitiles"
	"go.chromium.org/luci/common/proto/git"
	gitilespb "go.chromium.org/luci/common/proto/gitiles"
)

// gitilesClientWrapper provides utilities for interacting with a Gitiles project.
type gitilesClientWrapper struct {
	client  gitilespb.GitilesClient
	project string
}

// NewClient returns a gitilesClientWrapper for a host and project.
func NewClient(ctx context.Context, host, project string, httpClient *http.Client) (*gitilesClientWrapper, error) {
	client, err := gitiles.NewRESTClient(httpClient, host, true)
	if err != nil {
		return nil, err
	}
	return &gitilesClientWrapper{client: client, project: project}, nil
}

// LatestCommit resolves a ref to a revision.
func (c *gitilesClientWrapper) LatestCommit(ctx context.Context, ref string) (string, error) {
	log, err := c.Log(ctx, ref, 1)
	if err != nil {
		return "", err
	}
	return log[0].GetId(), nil
}

// Log returns a slice of commits of length `numCommits` starting from `committish`.
func (c *gitilesClientWrapper) Log(ctx context.Context, committish string, numCommits int32) ([]*git.Commit, error) {
	resp, err := c.client.Log(ctx, &gitilespb.LogRequest{
		Project:    c.project,
		Committish: committish,
		PageSize:   numCommits,
	})
	if err != nil {
		return nil, fmt.Errorf("failed to get log for project %s: %v", c.project, err)
	}
	if len(resp.Log) == 0 {
		return nil, fmt.Errorf("empty log for project %s", c.project)
	}
	return resp.Log, nil
}

// DownloadFile returns the contents of the file at `path` and `ref`.
func (c *gitilesClientWrapper) DownloadFile(ctx context.Context, path, ref string) (string, error) {
	resp, err := c.client.DownloadFile(ctx, &gitilespb.DownloadFileRequest{
		Project:    c.project,
		Committish: ref,
		Path:       path,
		Format:     gitilespb.DownloadFileRequest_TEXT,
	})
	if err != nil {
		return "", fmt.Errorf("failed to download %s: %v", path, err)
	}
	return resp.Contents, nil
}