package codereview

import (
	"errors"
	"fmt"
	"sort"
	"strings"

	"go.skia.org/infra/go/gerrit"
	"go.skia.org/infra/go/github"
	"go.skia.org/infra/go/skerr"
	"go.skia.org/infra/go/util"
)

const (
	// GERRIT_CONFIG_ANDROID is a Gerrit server configuration used by
	// Android and related projects.
	GERRIT_CONFIG_ANDROID = "android"

	// GERRIT_CONFIG_ANGLE is a Gerrit server configuration used by ANGLE.
	GERRIT_CONFIG_ANGLE = "angle"

	// GERRIT_CONFIG_CHROMIUM is a Gerrit server configuration used by
	// Chromium and related projects.
	GERRIT_CONFIG_CHROMIUM = "chromium"

	// GERRIT_CONFIG_CHROMIUM_NO_CQ is a Gerrit server configuration used by
	// Chromium for projects with no Commit Queue.
	GERRIT_CONFIG_CHROMIUM_NO_CQ = "chromium-no-cq"

	// GERRIT_CONFIG_LIBASSISTANT is a Gerrit server configuration used by
	// libassistant.
	GERRIT_CONFIG_LIBASSISTANT = "libassistant"
)

var (
	// GERRIT_CONFIGS maps Gerrit config names to gerrit.Configs.
	GERRIT_CONFIGS = map[string]*gerrit.Config{
		GERRIT_CONFIG_ANDROID:        gerrit.CONFIG_ANDROID,
		GERRIT_CONFIG_ANGLE:          gerrit.CONFIG_ANGLE,
		GERRIT_CONFIG_CHROMIUM:       gerrit.CONFIG_CHROMIUM,
		GERRIT_CONFIG_CHROMIUM_NO_CQ: gerrit.CONFIG_CHROMIUM_NO_CQ,
		GERRIT_CONFIG_LIBASSISTANT:   gerrit.CONFIG_LIBASSISTANT,
	}
)

// CodeReviewConfig provides generalized configuration information for a code
// review service.
type CodeReviewConfig interface {
	util.Validator

	// Init creates a CodeReview object based on this CodeReviewConfig.
	Init(gerrit.GerritInterface, *github.GitHub) (CodeReview, error)
}

// GerritConfig provides configuration for Gerrit.
type GerritConfig struct {
	// Gerrit host URL.
	URL string `json:"url"`

	// Project name for uploaded CLs.
	Project string `json:"project"`

	// Gerrit instance configuration. This informs the roller which labels
	// to set, among other things. The value should be one of the
	// GERRIT_CONFIG_ constants in this package.
	Config string `json:"config"`
}

// See documentation for util.Validator interface.
func (c *GerritConfig) Validate() error {
	if c.URL == "" {
		return errors.New("URL is required.")
	}
	if c.Project == "" {
		return errors.New("Project is required.")
	}
	if _, ok := GERRIT_CONFIGS[c.Config]; !ok {
		validConfigs := make([]string, 0, len(GERRIT_CONFIGS))
		for name := range GERRIT_CONFIGS {
			validConfigs = append(validConfigs, name)
		}
		sort.Strings(validConfigs)
		return fmt.Errorf("Config must be one of: [%s]", strings.Join(validConfigs, ", "))
	}
	return nil
}

// See documentation for CodeReviewConfig interface.
func (c *GerritConfig) Init(gerritClient gerrit.GerritInterface, githubClient *github.GitHub) (CodeReview, error) {
	return newGerritCodeReview(c, gerritClient)
}

// GetConfig returns the gerrit.Config referenced by the GerritConfig.
func (c *GerritConfig) GetConfig() (*gerrit.Config, error) {
	cfg, ok := GERRIT_CONFIGS[c.Config]
	if !ok {
		return nil, skerr.Fmt("Unknown Gerrit config %q", c.Config)
	}
	return cfg, nil
}

// CanQueryTrybots returns true if we can query for trybot results.
func (c *GerritConfig) CanQueryTrybots() bool {
	return c.Config != GERRIT_CONFIG_ANDROID
}

// GithubConfig provides configuration for Github.
type GithubConfig struct {
	RepoOwner      string   `json:"repoOwner,omitempty"`
	RepoName       string   `json:"repoName,omitempty"`
	ChecksNum      int      `json:"checksNum,omitempty"`
	ChecksWaitFor  []string `json:"checksWaitFor,omitempty"`
	MergeMethodURL string   `json:"mergeMethodURL,omitempty"`
}

// See documentation for util.Validator interface.
func (c *GithubConfig) Validate() error {
	if c.RepoOwner == "" {
		return errors.New("RepoOwner is required.")
	}
	if c.RepoName == "" {
		return errors.New("RepoName is required.")
	}
	if c.ChecksNum == 0 {
		return errors.New("At least one check is required.")
	}
	return nil
}

// See documentation for CodeReviewConfig interface.
func (c *GithubConfig) Init(gerritClient gerrit.GerritInterface, githubClient *github.GitHub) (CodeReview, error) {
	return newGithubCodeReview(c, githubClient)
}

// Google3 config is an empty configuration object for Google3.
type Google3Config struct{}

// See documentation for util.Validator interface.
func (c *Google3Config) Validate() error {
	return nil
}

// See documentation for CodeReviewConfig interface.
func (c *Google3Config) Init(gerrit.GerritInterface, *github.GitHub) (CodeReview, error) {
	return nil, errors.New("Init not implemented for Google3Config.")
}