package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"sort"
	"strings"

	"github.com/hashicorp/go-version"
	"github.com/matrix-org/gomatrixserverlib/fclient"
	"github.com/matrix-org/gomatrixserverlib/spec"
	"maunium.net/go/mautrix"
	"maunium.net/go/mautrix/id"
)

type ServerPath struct {
	MaxRoomVersion string
	Server         string
}

type VersionPath struct {
	MaxRoomVersion string
	Server         string
	Version        string
}

var unknownServerVersionInfo = fclient.Version{
	Server: struct {
		Name    string `json:"name"`
		Version string `json:"version"`
	}{
		Name:    "unknown",
		Version: "unknown",
	},
}

// Gets the maximum supported room version for the given server-version-pair.
func getMaxRoomVersion(serverVersionInfo fclient.Version) string {
	// Use only the first part of the version string as sometimes there are suffixes after a space, like " (<commit>)", which then can't be parsed.
	serverVersion, err := version.NewVersion(strings.Split(serverVersionInfo.Server.Version, " ")[0])
	if err != nil {
		return "unkown"
	}

	switch serverVersionInfo.Server.Name {
	case "Conduit":
		// https://conduit.rs/
		// https://conduit.rs/changelog/
		// https://gitlab.com/famedly/conduit
		switch {
		// https://conduit.rs/changelog/#v0-10-8-2025-08-11
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.10.8"))):
			return "v12"
		// https://conduit.rs/changelog/#v0-7-0-2024-04-25
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.7.0"))):
			return "v11"
		// https://conduit.rs/changelog/#v0-5-0-2022-12-21
		// Includes MR 400:
		// https://gitlab.com/famedly/conduit/-/merge_requests/400/commits
		// MR 400 includes a commit, which specifies v10 as stable.
		// https://gitlab.com/famedly/conduit/-/commit/1e1a144dfa98429ef9f02d16045796b73013830d
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.5.0"))):
			return "v10"
		// https://conduit.rs/changelog/#v0-4-0-2022-06-23
		// Includes MR 257:
		// https://gitlab.com/famedly/conduit/-/merge_requests/257/commits
		// MR 257 includes a commit, which specifies added support v7 to v9.
		// https://gitlab.com/famedly/conduit/-/commit/0ae39807a478370a769217d01fa33514299a2b35
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.4.0"))):
			return "v9"
		// https://conduit.rs/changelog/#v0-2-0-2021-09-01
		default:
			return "v6"
		}
	case "conduwuit", "Conduwuit":
		// Using continuwuitys source (history) as a reference:
		// https://forgejo.ellis.link/continuwuation/continuwuity

		// History from first commit on "continuwuity":
		// https://forgejo.ellis.link/continuwuation/continuwuity/commits/commit/e054a56b3286a6fb3091bedd5261089435ed26d1
		// Last commit on "conduwuit"/"Conduwuit":
		// https://forgejo.ellis.link/continuwuation/continuwuity/src/commit/d8311a5ff672fdc4729d956af5e3af8646b0670d
		// Last version was "0.5.0":
		// https://forgejo.ellis.link/continuwuation/continuwuity/src/commit/d8311a5ff672fdc4729d956af5e3af8646b0670d/Cargo.toml

		// Matching both "conduwuit" and "Conduwuit" as the capitalization got changed.
		// https://forgejo.ellis.link/continuwuation/continuwuity/commit/5b5ccba64e3d36a9235f4e0d449f40d859046dad

		switch {
		// Since the version went from "0.7.0-<something>" to "0.3.0" and the last version was "0.5.0", give all versions greater than "0.7.0" a lower max room version.
		// https://forgejo.ellis.link/continuwuation/continuwuity/commit/af0b81f5fb737d3550cf22fbcf8d8b8eb1947408
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.7.0"))):
			return "v10"
		// v11 support (shows there as included in tag "v0.3.0"):
		// https://forgejo.ellis.link/continuwuation/continuwuity/commit/223f05c922ea6f3085d386f0758df550459a25c3
		// Tag "v0.3.0":
		// https://forgejo.ellis.link/continuwuation/continuwuity/src/tag/v0.3.0/src/service/globals/mod.rs#L130
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.3.0"))):
			return "v11"
		// First version named "Conduwuit"/"conduwuit":
		// https://forgejo.ellis.link/continuwuation/continuwuity/commit/e71855cd0b59d9274e8528a4c1ee480f99006c3c
		// v10 support at first version named "Conduwuit"/"conduwuit":
		// https://forgejo.ellis.link/continuwuation/continuwuity/src/commit/e71855cd0b59d9274e8528a4c1ee480f99006c3c/src/service/globals/mod.rs#L187
		// And shows first version as "0.7.0-alpha+conduwuit-0.1.3":
		// https://forgejo.ellis.link/continuwuation/continuwuity/src/commit/e71855cd0b59d9274e8528a4c1ee480f99006c3c/Cargo.toml
		// Because of this versioning and the match on "0.7.0" before, this default should never match, but it is included for clarity.
		default:
			return "v10"
		}
	case "continuwuity":
		// https://continuwuity.org/
		// https://forgejo.ellis.link/continuwuation/continuwuity

		// First version named "continuwuity":
		// https://forgejo.ellis.link/continuwuation/continuwuity/commit/dc599db19c48ad3cbae15fc419c4a531d217ed05
		// v11 support at first version named "continuwuity":
		// https://forgejo.ellis.link/continuwuation/continuwuity/src/commit/dc599db19c48ad3cbae15fc419c4a531d217ed05/src/core/info/room_version.rs
		return "v11"
	case "Dendrite":
		// https://github.com/element-hq/dendrite
		// https://element-hq.github.io/dendrite/
		// https://github.com/element-hq/dendrite/blob/main/CHANGES.md
		switch {
		// https://github.com/element-hq/dendrite/blob/v0.15.0/CHANGES.md#dendrite-0150-2025-08-12
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.15.0"))):
			return "v12"
		// https://github.com/matrix-org/dendrite/blob/v0.13.3/CHANGES.md#dendrite-0133-2023-09-28
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.13.3"))):
			return "v11"
		// https://github.com/matrix-org/dendrite/blob/v0.8.7/CHANGES.md#dendrite-087-2022-06-01
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.8.7"))):
			return "v10"
		// https://github.com/matrix-org/dendrite/blob/v0.8.6/CHANGES.md#dendrite-086-2022-05-26
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.8.6"))):
			return "v9"
		// https://github.com/matrix-org/dendrite/blob/v0.8.6/CHANGES.md#dendrite-086-2022-05-26
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.8.6"))):
			return "v8"
		// https://github.com/matrix-org/dendrite/blob/v0.4.1/CHANGES.md#dendrite-041-2021-07-26
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.4.1"))):
			return "v7"
		// https://github.com/matrix-org/dendrite/blob/v0.1.0/CHANGES.md#dendrite-010-2020-10-08
		default:
			return "v6"
		}
	case "Synapse":
		// https://github.com/element-hq/synapse/
		// https://element-hq.github.io/synapse/latest/
		// https://github.com/element-hq/synapse/blob/develop/CHANGES.md
		// https://github.com/element-hq/synapse/blob/develop/docs/changelogs/
		switch {
		// https://github.com/element-hq/synapse/blob/v1.135.1/CHANGES.md#synapse-11351-2025-08-11
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("1.135.1"))):
			return "v12"
		// https://github.com/element-hq/synapse/blob/v1.89.0rc1/CHANGES.md#synapse-1890rc1-2023-07-25
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("1.89.0rc1"))):
			return "v11"
		// https://github.com/element-hq/synapse/blob/v1.64.0rc1/CHANGES.md#synapse-1640rc1-2022-07-26
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("1.64.0rc1"))):
			return "v10"
		// https://github.com/element-hq/synapse/blob/v1.42.0rc2/CHANGES.md#synapse-1420rc2-2021-09-06
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("1.42.0rc2"))):
			return "v9"
		// https://github.com/element-hq/synapse/blob/v1.40.0rc3/CHANGES.md#synapse-1400rc3-2021-08-09
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("1.40.0rc3"))):
			return "v8"
		// https://github.com/element-hq/synapse/blob/v1.37.0rc1/CHANGES.md#synapse-1370rc1-2021-06-24
		// https://github.com/matrix-org/synapse/pull/10167
		// https://github.com/matrix-org/synapse/pull/10167/files#diff-8e36e2fc4dec5d84357ee3d140ad223b66fb36e630c25bbb45382ca59cdb0f40
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("1.37.0rc1"))):
			return "v7"
		// https://github.com/element-hq/synapse/blob/v1.14.0rc1/CHANGES.md#synapse-1140rc1-2020-05-26
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("1.14.0rc1"))):
			return "v6"
		// https://github.com/element-hq/synapse/blob/v1.0.0rc1/CHANGES.md#synapse-100rc1-2019-06-07
		// https://github.com/matrix-org/synapse/pull/5354
		// https://github.com/matrix-org/synapse/pull/5354/files#diff-8e36e2fc4dec5d84357ee3d140ad223b66fb36e630c25bbb45382ca59cdb0f40
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("1.0.0rc1"))):
			return "v5"
		// https://github.com/element-hq/synapse/blob/v0.99.5rc1/CHANGES.md#synapse-0995rc1-2019-05-21
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.99.5rc1"))):
			return "v4"
		// https://github.com/element-hq/synapse/blob/v0.99.0rc1/CHANGES.md#synapse-0990rc1-2019-01-30
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.99.0rc1"))):
			return "v3"
		// https://github.com/element-hq/synapse/blob/v0.34.1rc1/CHANGES.md#synapse-0341rc1-2019-01-08
		// https://github.com/matrix-org/synapse/pull/4307
		// https://github.com/matrix-org/synapse/pull/4307/files#diff-32e0f096397b0e3545054c51c42b5be4f0db953083b60d76a047cb1618f6b877
		case serverVersion.GreaterThanOrEqual(version.Must(version.NewVersion("0.34.1rc1"))):
			return "v2"
		default:
			return "v1"
		}
	case "Tuwunel":
		// https://github.com/matrix-construct/tuwunel

		// First version named "Tuwunel":
		// https://github.com/matrix-construct/tuwunel/commit/9b658d86b2f49d01ba8d2f5ae7f263a104e8f282#diff-d58f31e506570d0bcb7629251ec1b350c5dde4a205a338349f154f3fd3187e93
		// v11 support at first version named "Tuwunel":
		// https://github.com/matrix-construct/tuwunel/blob/9b658d86b2f49d01ba8d2f5ae7f263a104e8f282/src/core/info/room_version.rs
		return "v11"
	default:
		return "unkown"
	}
}

func main() {
	userLocalpart := os.Getenv("MATRIX_USER_LOCALPART")
	homeserver := os.Getenv("MATRIX_HOMESERVER")
	token := os.Getenv("MATRIX_TOKEN")
	room := os.Getenv("MATRIX_ROOM")
	verbose := false

	client, err := mautrix.NewClient(
		homeserver,
		id.NewUserID(userLocalpart, homeserver),
		token,
	)
	if err != nil {
		log.Fatal(err)
	}
	federationClient := fclient.NewClient(
		fclient.WithWellKnownSRVLookups(true),
	)

	joinedMembers, err := client.JoinedMembers(context.Background(), id.RoomID(room))
	if err != nil {
		log.Fatal(err)
	}

	membersByHomeservers := make(map[string]uint)
	for key := range joinedMembers.Joined {
		membersByHomeservers[key.Homeserver()]++
	}

	// Info map tree.
	maxRoomVersionInfo := make(map[string](map[string](map[string](map[string]uint))))
	// Member counters.
	membersByMaxRoomVersion := make(map[string]uint)
	membersByServerPath := make(map[ServerPath]uint)
	membersByVersionPath := make(map[VersionPath]uint)

	for key, value := range membersByHomeservers {
		serverVersionInfo, err := federationClient.GetVersion(context.Background(), spec.ServerName(key))
		if err != nil {
			serverVersionInfo = unknownServerVersionInfo
		}

		maxRoomVersion := getMaxRoomVersion(serverVersionInfo)

		// Add to counters.
		membersByMaxRoomVersion[maxRoomVersion] += value
		membersByServerPath[ServerPath{maxRoomVersion, serverVersionInfo.Server.Name}] += value
		membersByVersionPath[VersionPath{maxRoomVersion, serverVersionInfo.Server.Name, serverVersionInfo.Server.Version}] += value

		// Sort into maxRoomVersionInfo map tree.
		serverMap, ok := maxRoomVersionInfo[maxRoomVersion]
		if !ok {
			serverMap = make(map[string](map[string](map[string]uint)))
			maxRoomVersionInfo[maxRoomVersion] = serverMap
		}
		versionMap, ok := serverMap[serverVersionInfo.Server.Name]
		if !ok {
			versionMap = make(map[string](map[string]uint))
			serverMap[serverVersionInfo.Server.Name] = versionMap
		}
		homeserverMap, ok := versionMap[serverVersionInfo.Server.Version]
		if !ok {
			homeserverMap = make(map[string]uint)
			versionMap[serverVersionInfo.Server.Version] = homeserverMap
		}
		homeserverMap[key] = value
	}

	fmt.Println("Room:")
	fmt.Printf("%s -> %d\n\n", room, len(joinedMembers.Joined))

	fmt.Println("Version Support:")

	maxRoomVersionKeys := make([]string, 0, len(maxRoomVersionInfo))
	for key := range maxRoomVersionInfo {
		maxRoomVersionKeys = append(maxRoomVersionKeys, key)
	}
	sort.Strings(maxRoomVersionKeys)
	for _, maxRoomVersionKey := range maxRoomVersionKeys {
		maxRoomVersionValue := maxRoomVersionInfo[maxRoomVersionKey]

		fmt.Printf("%s -> %d\n", maxRoomVersionKey, membersByMaxRoomVersion[maxRoomVersionKey])

		serverKeys := make([]string, 0, len(maxRoomVersionValue))
		for key := range maxRoomVersionValue {
			serverKeys = append(serverKeys, key)
		}
		sort.Strings(serverKeys)
		for _, serverKey := range serverKeys {
			serverValue := maxRoomVersionValue[serverKey]

			fmt.Printf("  %s -> %d\n", serverKey, membersByServerPath[ServerPath{maxRoomVersionKey, serverKey}])

			versionKeys := make([]string, 0, len(serverValue))
			for key := range serverValue {
				versionKeys = append(versionKeys, key)
			}
			sort.Strings(versionKeys)
			for _, versionKey := range versionKeys {
				versionValue := serverValue[versionKey]

				fmt.Printf("    %s -> %d\n", versionKey, membersByVersionPath[VersionPath{maxRoomVersionKey, serverKey, versionKey}])

				if verbose {
					homeserverKeys := make([]string, 0, len(versionValue))
					for key := range versionValue {
						homeserverKeys = append(homeserverKeys, key)
					}
					sort.Strings(homeserverKeys)
					for _, homeserverKey := range homeserverKeys {
						homeserverValue := versionValue[homeserverKey]

						fmt.Printf("      %s -> %d\n", homeserverKey, homeserverValue)
					}
				}
			}
		}
	}
}