// Copyright 2018 The LUCI Authors.
//
// 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 frontend

import (
	"fmt"
	"net/http"
	"strconv"
	"strings"

	bb "go.chromium.org/luci/buildbucket"
	buildbucketpb "go.chromium.org/luci/buildbucket/proto"
	bbv1 "go.chromium.org/luci/common/api/buildbucket/buildbucket/v1"
	"go.chromium.org/luci/common/data/strpair"
	"go.chromium.org/luci/common/errors"
	"go.chromium.org/luci/common/logging"
	"go.chromium.org/luci/milo/buildsource/buildbucket"
	"go.chromium.org/luci/milo/common"
	"go.chromium.org/luci/milo/frontend/ui"
	"go.chromium.org/luci/server/router"
	"go.chromium.org/luci/server/templates"
)

// handleDevBuild renders a canned build for development.
func handleDevBuild(c *router.Context) error {
	name := c.Params.ByName("name")
	b, err := buildbucket.GetTestBuild(c.Context, "../../buildsource/buildbucket", name)
	if err != nil {
		return err
	}
	return renderBuild(c, &ui.BuildPage{Build: *b}, nil)
}

// handleLUCIBuild renders a LUCI build.
func handleLUCIBuild(c *router.Context) error {
	bucket := c.Params.ByName("bucket")
	buildername := c.Params.ByName("builder")
	numberOrId := c.Params.ByName("numberOrId")

	if _, v2Bucket := bb.BucketNameToV2(bucket); v2Bucket != "" {
		// Params bucket is a v1 bucket, so call the legacy endpoint.
		return handleLUCIBuildLegacy(c, bucket, buildername, numberOrId)
	}

	// TODO(hinoka): Once v2 is default, redirect v1 bucketnames to v2 bucketname URLs.
	br := buildbucketpb.GetBuildRequest{}
	if strings.HasPrefix(numberOrId, "b") {
		id, err := strconv.ParseInt(numberOrId[1:], 10, 64)
		if err != nil {
			return errors.Annotate(err, "bad build id").Tag(common.CodeParameterError).Err()
		}
		br.Id = int64(id)
	} else {
		number, err := strconv.Atoi(numberOrId)
		if err != nil {
			return errors.Annotate(err, "bad build number").Tag(common.CodeParameterError).Err()
		}
		br.BuildNumber = int32(number)
		br.Builder = &buildbucketpb.BuilderID{
			Project: c.Params.ByName("project"),
			Bucket:  bucket,
			Builder: buildername,
		}
	}

	bp, err := buildbucket.GetBuildPage(c, br)
	return renderBuild(c, bp, err)
}

// renderBuild is a shortcut for rendering build or returning err if it is not nil.
func renderBuild(c *router.Context, bp *ui.BuildPage, err error) error {
	if err != nil {
		return err
	}

	bp.StepDisplayPref = getStepDisplayPrefCookie(c)

	templates.MustRender(c.Context, c.Writer, "pages/build.html", templates.Args{
		"BuildPage": bp,
	})
	return nil
}

// redirectLUCIBuild redirects to a canonical build URL
// e.g. to /p/{project}/builders/{bucket}/{builder}/{number or id}.
func redirectLUCIBuild(c *router.Context) error {
	idStr := c.Params.ByName("id")
	// Verify it is an int64.
	if _, err := strconv.ParseInt(idStr, 10, 64); err != nil {
		return errors.Annotate(err, "invalid id").Tag(common.CodeParameterError).Err()
	}

	build, err := buildbucket.GetRawBuild(c.Context, idStr)
	if err != nil {
		return err
	}

	// If the build has a number, redirect to a URL with it.
	builder := ""
	u := *c.Request.URL
	for _, t := range build.Tags {
		switch k, v := strpair.Parse(t); k {
		case bbv1.TagBuildAddress:
			_, project, bucket, builder, number, _ := bbv1.ParseBuildAddress(v)
			if number > 0 {
				u.Path = fmt.Sprintf("/p/%s/builders/%s/%s/%d", project, bucket, builder, number)
				http.Redirect(c.Writer, c.Request, u.String(), http.StatusMovedPermanently)
				return nil
			}

		case bbv1.TagBuilder:
			builder = v
		}
	}
	if builder == "" {
		return errors.Reason("build %s does not have a builder", idStr).Tag(common.CodeParameterError).Err()
	}

	u.Path = fmt.Sprintf("/p/%s/builders/%s/%s/b%d", build.Project, build.Bucket, builder, build.Id)
	http.Redirect(c.Writer, c.Request, u.String(), http.StatusMovedPermanently)
	return nil
}

func getStepDisplayPrefCookie(c *router.Context) ui.StepDisplayPref {
	switch cookie, err := c.Request.Cookie("stepDisplayPref"); err {
	case nil:
		return ui.StepDisplayPref(cookie.Value)
	case http.ErrNoCookie:
		return ui.StepDisplayDefault
	default:
		logging.WithError(err).Errorf(c.Context, "failed to read stepDisplayPref cookie")
		return ui.StepDisplayDefault
	}
}