Implement more issue filters (#400)

This adds new filters to `tea issues ls` and `tea pr ls`, made available in SDK 0.15:

```
--state value                 Filter by state (all|open|closed) (default: open)
--keyword value, -k value     Filter by search string
--labels value, -L value      Comma-separated list of labels to match issues against.
--milestones value, -m value  Comma-separated list of milestones to match issues against.
--author value, -A value
--assignee value, -a value
--mentions value, -M value
--from value, -F value        Filter by activity after this date
--until value, -u value       Filter by activity before this date
```

Note: I felt free to change parameter names as exposed by SDK & API, as the names exposed by them are partially bollocks (eg `mentioned_by`) and or inconsistent with usage in other commands (eg `tea times --until`)

fixes #376, related #323

Co-authored-by: Norwin <git@nroo.de>
Reviewed-on: https://gitea.com/gitea/tea/pulls/400
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-by: 6543 <6543@obermui.de>
Co-authored-by: Norwin <noerw@noreply.gitea.io>
Co-committed-by: Norwin <noerw@noreply.gitea.io>

cmd/flags/generic.go

@@ -0,0 +1,106 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package flags
+
+import (
+	"github.com/urfave/cli/v2"
+)
+
+// LoginFlag provides flag to specify tea login profile
+var LoginFlag = cli.StringFlag{
+	Name:    "login",
+	Aliases: []string{"l"},
+	Usage:   "Use a different Gitea Login. Optional",
+}
+
+// RepoFlag provides flag to specify repository
+var RepoFlag = cli.StringFlag{
+	Name:    "repo",
+	Aliases: []string{"r"},
+	Usage:   "Override local repository path or gitea repository slug to interact with. Optional",
+}
+
+// RemoteFlag provides flag to specify remote repository
+var RemoteFlag = cli.StringFlag{
+	Name:    "remote",
+	Aliases: []string{"R"},
+	Usage:   "Discover Gitea login from remote. Optional",
+}
+
+// OutputFlag provides flag to specify output type
+var OutputFlag = cli.StringFlag{
+	Name:    "output",
+	Aliases: []string{"o"},
+	Usage:   "Output format. (csv, simple, table, tsv, yaml)",
+}
+
+// PaginationPageFlag provides flag for pagination options
+var PaginationPageFlag = cli.StringFlag{
+	Name:    "page",
+	Aliases: []string{"p"},
+	Usage:   "specify page, default is 1",
+}
+
+// PaginationLimitFlag provides flag for pagination options
+var PaginationLimitFlag = cli.StringFlag{
+	Name:    "limit",
+	Aliases: []string{"lm"},
+	Usage:   "specify limit of items per page",
+}
+
+// LoginOutputFlags defines login and output flags that should
+// added to all subcommands and appended to the flags of the
+// subcommand to work around issue and provide --login and --output:
+// https://github.com/urfave/cli/issues/585
+var LoginOutputFlags = []cli.Flag{
+	&LoginFlag,
+	&OutputFlag,
+}
+
+// LoginRepoFlags defines login and repo flags that should
+// be used for all subcommands and appended to the flags of
+// the subcommand to work around issue and provide --login and --repo:
+// https://github.com/urfave/cli/issues/585
+var LoginRepoFlags = []cli.Flag{
+	&LoginFlag,
+	&RepoFlag,
+	&RemoteFlag,
+}
+
+// AllDefaultFlags defines flags that should be available
+// for all subcommands working with dedicated repositories
+// to work around issue and provide --login, --repo and --output:
+// https://github.com/urfave/cli/issues/585
+var AllDefaultFlags = append([]cli.Flag{
+	&RepoFlag,
+	&RemoteFlag,
+}, LoginOutputFlags...)
+
+// NotificationFlags defines flags that should be available on notifications.
+var NotificationFlags = append([]cli.Flag{
+	NotificationStateFlag,
+	&cli.BoolFlag{
+		Name:    "mine",
+		Aliases: []string{"m"},
+		Usage:   "Show notifications across all your repositories instead of the current repository only",
+	},
+	&PaginationPageFlag,
+	&PaginationLimitFlag,
+}, AllDefaultFlags...)
+
+// NotificationStateFlag is a csv flag applied to all notification subcommands as filter
+var NotificationStateFlag = NewCsvFlag(
+	"states",
+	"notification states to filter by",
+	[]string{"s"},
+	[]string{"pinned", "unread", "read"},
+	[]string{"unread", "pinned"},
+)
+
+// FieldsFlag generates a flag selecting printable fields.
+// To retrieve the value, use f.GetValues()
+func FieldsFlag(availableFields, defaultFields []string) *CsvFlag {
+	return NewCsvFlag("fields", "fields to print", []string{"f"}, availableFields, defaultFields)
+}