[feature] Conversations API (#3013)

* Implement conversations API

* Sort and page conversations by last status ID

* Appease linter

* Fix deleting conversations and statuses

* Refactor to make migrations automatic

* Lint

* Update tests post-merge

* Fixes from live-fire testing

* Linter caught a format problem

* Refactor tests, fix cache

* Negative test for non-DMs

* Run conversations advanced migration on testrig startup as well as regular server startup

* Document (lack of) side effects of API method for deleting a conversation

* Make not-found check less nested for readability

* Rename PutConversation to UpsertConversation

* Use util.Ptr instead of IIFE

* Reduce cache used by conversations

* Remove unnecessary TableExpr/ColumnExpr

* Use struct tags for both unique constraints on Conversation

* Make it clear how paging with GetDirectStatusIDsBatch should be used

* Let conversation paging skip conversations it can't render

* Use Bun NewDropTable

* Convert delete raw query to Bun

* Convert update raw query to Bun

* Convert latestConversationStatusesTempTable raw query partially to Bun

* Convert conversationStatusesTempTable raw query partially to Bun

* Rename field used to store result of MaxDirectStatusID

* Move advanced migrations to their own tiny processor

* Catch up util function name with main

* Remove json.… wrappers

* Remove redundant check

* Combine error checks

* Replace map with slice of structs

* Address processor/type converter comments

- Add context info for errors
- Extract some common processor code into shared methods
- Move conversation eligibility check ahead of populating conversation

* Add error context when dropping temp tables

1 files changed, 34 insertions, 10 deletions

diff --git a/internal/api/client/conversations/conversationsget.go b/internal/api/client/conversations/conversationsget.go
index 11bddb1ce..663b9a707 100644
--- a/internal/api/client/conversations/conversationsget.go
+++ b/internal/api/client/conversations/conversationsget.go
@@ -24,14 +24,13 @@ import (
 	apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
 )
 
 // ConversationsGETHandler swagger:operation GET /api/v1/conversations conversationsGet
 //
 // Get an array of (direct message) conversations that requesting account is involved in.
 //
-// NOT IMPLEMENTED YET: Will currently always return an array of length 0.
-//
 // The next and previous queries can be parsed from the returned Link header.
 // Example:
 //
@@ -51,26 +50,26 @@ import (
 //		name: max_id
 //		type: string
 //		description: >-
-//			Return only conversations *OLDER* than the given max ID.
+//			Return only conversations with last statuses *OLDER* than the given max ID.
 //			The conversation with the specified ID will not be included in the response.
-//			NOTE: the ID is of the internal conversation, use the Link header for pagination.
+//			NOTE: The ID is a status ID. Use the Link header for pagination.
 //		in: query
 //		required: false
 //	-
 //		name: since_id
 //		type: string
 //		description: >-
-//			Return only conversations *NEWER* than the given since ID.
+//			Return only conversations with last statuses *NEWER* than the given since ID.
 //			The conversation with the specified ID will not be included in the response.
-//			NOTE: the ID is of the internal conversation, use the Link header for pagination.
+//			NOTE: The ID is a status ID. Use the Link header for pagination.
 //		in: query
 //	-
 //		name: min_id
 //		type: string
 //		description: >-
-//			Return only conversations *IMMEDIATELY NEWER* than the given min ID.
+//			Return only conversations with last statuses *IMMEDIATELY NEWER* than the given min ID.
 //			The conversation with the specified ID will not be included in the response.
-//			NOTE: the ID is of the internal conversation, use the Link header for pagination.
+//			NOTE: The ID is a status ID. Use the Link header for pagination.
 //		in: query
 //		required: false
 //	-
@@ -108,7 +107,8 @@ import (
 //		'500':
 //			description: internal server error
 func (m *Module) ConversationsGETHandler(c *gin.Context) {
-	if _, err := oauth.Authed(c, true, true, true, true); err != nil {
+	authed, err := oauth.Authed(c, true, true, true, true)
+	if err != nil {
 		apiutil.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGetV1)
 		return
 	}
@@ -118,5 +118,29 @@ func (m *Module) ConversationsGETHandler(c *gin.Context) {
 		return
 	}
 
-	apiutil.Data(c, http.StatusOK, apiutil.AppJSON, apiutil.EmptyJSONArray)
+	page, errWithCode := paging.ParseIDPage(c,
+		1,  // min limit
+		80, // max limit
+		40, // default limit
+	)
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	resp, errWithCode := m.processor.Conversations().GetAll(
+		c.Request.Context(),
+		authed.Account,
+		page,
+	)
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	if resp.LinkHeader != "" {
+		c.Header("Link", resp.LinkHeader)
+	}
+
+	apiutil.JSON(c, http.StatusOK, resp.Items)
 }