{{- $existingSecret := lookup "v1" "Secret" .Release.Namespace (printf "%s-credentials" .Release.Name) }}
{{- $passwords := dict }}

{{- with (index $existingSecret "data") }}
  {{- range $k, $v := . }}
    {{- $_ := set $passwords $k (b64dec $v) }}
  {{- end }}
{{- end }}

{{- range $user, $u := .Values.users }}
  {{- if $u.password }}
    {{- $_ := set $passwords $user $u.password }}
  {{- else if not (index $passwords $user) }}
    {{- $_ := set $passwords $user (randAlphaNum 16) }}
  {{- end }}
{{- end }}

{{- if .Values.users }}
apiVersion: v1
kind: Secret
metadata:
  name: {{ .Release.Name }}-credentials
stringData:
  {{- range $user, $u := .Values.users }}
  {{ quote $user }}: {{ quote (index $passwords $user) }}
  {{- end }}
{{- end }}
---
apiVersion: v1
kind: Secret
metadata:
  name: {{ .Release.Name }}-init-script
stringData:
  init.sh: |
    #!/bin/bash
    set -e

    until pg_isready ; do sleep 5; done

    echo "== create users"
    {{- if and .Values.users (not (hasKey .Values.users "postgres")) }}
    psql -v ON_ERROR_STOP=1 <<\EOT
    {{- range $user, $u := .Values.users }}
    SELECT 'CREATE ROLE "{{ $user }}" LOGIN INHERIT;'
    WHERE NOT EXISTS (SELECT FROM pg_catalog.pg_roles WHERE rolname = '{{ $user }}')\gexec
    ALTER ROLE "{{ $user }}" WITH PASSWORD '{{ index $passwords $user }}' LOGIN INHERIT {{ ternary "REPLICATION" "NOREPLICATION" (default false $u.replication) }};
    COMMENT ON ROLE "{{ $user }}" IS 'user managed by helm';
    {{- end }}
    EOT
    {{- else if and .Values.users (hasKey .Values.users "postgres") }}
    {{- fail "`users.postgres` is forbidden by policy. Use a different username." }}
    {{- end }}

    echo "== delete users"
    MANAGED_USERS=$(echo '\du+' | psql | awk -F'|' '$4 == " user managed by helm" {print $1}' | awk NF=NF RS= OFS=' ')
    DEFINED_USERS="{{ join " " (keys .Values.users) }}"
    DELETE_USERS=$(for user in $MANAGED_USERS; do case " $DEFINED_USERS " in *" $user "*) :;; *) echo $user;; esac; done)

    echo "users to delete: $DELETE_USERS"
    for user in $DELETE_USERS; do
    # https://stackoverflow.com/a/51257346/2931267
    psql -v ON_ERROR_STOP=1 --echo-all <<EOT
    REASSIGN OWNED BY $user TO postgres;
    DROP OWNED BY $user;
    DROP USER $user;
    EOT
    done

    echo "== create databases and roles"
    {{- if .Values.databases }}
    psql -v ON_ERROR_STOP=1 --echo-all <<\EOT
    {{- range $database, $d := .Values.databases }}
    SELECT 'CREATE DATABASE "{{ $database }}"'
    WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = '{{ $database }}')\gexec
    COMMENT ON DATABASE "{{ $database }}" IS 'database managed by helm';
    SELECT 'CREATE ROLE "{{ $database }}_admin" NOINHERIT;'
    WHERE NOT EXISTS (SELECT FROM pg_catalog.pg_roles WHERE rolname = '{{ $database }}_admin')\gexec
    COMMENT ON ROLE "{{ $database }}_admin" IS 'role managed by helm';
    SELECT 'CREATE ROLE "{{ $database }}_readonly" NOINHERIT;'
    WHERE NOT EXISTS (SELECT FROM pg_catalog.pg_roles WHERE rolname = '{{ $database }}_readonly')\gexec
    COMMENT ON ROLE "{{ $database }}_readonly" IS 'role managed by helm';
    {{- end }}
    EOT
    {{- end }}

    echo "== grant privileges on databases to roles"
    {{- range $database, $d := .Values.databases }}
    psql -v ON_ERROR_STOP=1 --echo-all -d "{{ $database }}" <<\EOT
    ALTER DATABASE "{{ $database }}" OWNER TO "{{ $database }}_admin";
    GRANT CONNECT ON DATABASE "{{ $database }}" TO "{{ $database }}_readonly";

    DO $$
    DECLARE
        schema_record record;
    BEGIN
        -- Loop over all schemas
        FOR schema_record IN SELECT schema_name FROM information_schema.schemata WHERE schema_name NOT IN ('pg_catalog', 'information_schema') LOOP
            -- Changing Schema Ownership
            EXECUTE format('ALTER SCHEMA %I OWNER TO %I', schema_record.schema_name, '{{ $database }}_admin');

            -- Add rights for the admin role
            EXECUTE format('GRANT ALL ON SCHEMA %I TO %I', schema_record.schema_name, '{{ $database }}_admin');
            EXECUTE format('GRANT ALL ON ALL TABLES IN SCHEMA %I TO %I', schema_record.schema_name, '{{ $database }}_admin');
            EXECUTE format('GRANT ALL ON ALL SEQUENCES IN SCHEMA %I TO %I', schema_record.schema_name, '{{ $database }}_admin');
            EXECUTE format('GRANT ALL ON ALL FUNCTIONS IN SCHEMA %I TO %I', schema_record.schema_name, '{{ $database }}_admin');
            EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT ALL ON TABLES TO %I', schema_record.schema_name, '{{ $database }}_admin');
            EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT ALL ON SEQUENCES TO %I', schema_record.schema_name, '{{ $database }}_admin');
            EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT ALL ON FUNCTIONS TO %I', schema_record.schema_name, '{{ $database }}_admin');

            -- Add rights for the readonly role
            EXECUTE format('GRANT USAGE ON SCHEMA %I TO %I', schema_record.schema_name, '{{ $database }}_readonly');
            EXECUTE format('GRANT SELECT ON ALL TABLES IN SCHEMA %I TO %I', schema_record.schema_name, '{{ $database }}_readonly');
            EXECUTE format('GRANT USAGE ON ALL SEQUENCES IN SCHEMA %I TO %I', schema_record.schema_name, '{{ $database }}_readonly');
            EXECUTE format('GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA %I TO %I', schema_record.schema_name, '{{ $database }}_readonly');
            EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT SELECT ON TABLES TO %I', schema_record.schema_name, '{{ $database }}_readonly');
            EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT USAGE ON SEQUENCES TO %I', schema_record.schema_name, '{{ $database }}_readonly');
            EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT EXECUTE ON FUNCTIONS TO %I', schema_record.schema_name, '{{ $database }}_readonly');
        END LOOP;
    END$$;
    EOT

    echo "== setup event trigger for schema creation"
    psql -v ON_ERROR_STOP=1 --echo-all -d "{{ $database }}" <<\EOT
    CREATE OR REPLACE FUNCTION auto_grant_schema_privileges()
    RETURNS event_trigger LANGUAGE plpgsql AS $$
    DECLARE
        obj record;
    BEGIN
        FOR obj IN SELECT * FROM pg_event_trigger_ddl_commands() WHERE command_tag = 'CREATE SCHEMA' LOOP
        EXECUTE format('ALTER SCHEMA %I OWNER TO %I', obj.object_identity, '{{ $database }}_admin');
        EXECUTE format('GRANT ALL ON SCHEMA %I TO %I', obj.object_identity, '{{ $database }}_admin');
        EXECUTE format('GRANT USAGE ON SCHEMA %I TO %I', obj.object_identity, '{{ $database }}_readonly');
        EXECUTE format('GRANT SELECT ON ALL TABLES IN SCHEMA %I TO %I', obj.object_identity, '{{ $database }}_readonly');
        EXECUTE format('GRANT USAGE ON ALL SEQUENCES IN SCHEMA %I TO %I', obj.object_identity, '{{ $database }}_readonly');
        EXECUTE format('GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA %I TO %I', obj.object_identity, '{{ $database }}_readonly');

        -- Set owner for schema
        EXECUTE format('ALTER SCHEMA %I OWNER TO %I', obj.object_identity, '{{ $database }}_admin');

        -- Set privileges for admin role
        EXECUTE format('GRANT ALL ON SCHEMA %I TO %I', obj.object_identity, '{{ $database }}_admin');
        EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT ALL ON TABLES TO %I', obj.object_identity, '{{ $database }}_admin');
        EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT ALL ON SEQUENCES TO %I', obj.object_identity, '{{ $database }}_admin');
        EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT ALL ON FUNCTIONS TO %I', obj.object_identity, '{{ $database }}_admin');

        -- Set privileges for readonly role
        EXECUTE format('GRANT USAGE ON SCHEMA %I TO %I', obj.object_identity, '{{ $database }}_readonly');
        EXECUTE format('GRANT SELECT ON ALL TABLES IN SCHEMA %I TO %I', obj.object_identity, '{{ $database }}_readonly');
        EXECUTE format('GRANT USAGE ON ALL SEQUENCES IN SCHEMA %I TO %I', obj.object_identity, '{{ $database }}_readonly');
        EXECUTE format('GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA %I TO %I', obj.object_identity, '{{ $database }}_readonly');
        EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT SELECT ON TABLES TO %I', obj.object_identity, '{{ $database }}_readonly');
        EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT USAGE ON SEQUENCES TO %I', obj.object_identity, '{{ $database }}_readonly');
        EXECUTE format('ALTER DEFAULT PRIVILEGES IN SCHEMA %I GRANT EXECUTE ON FUNCTIONS TO %I', obj.object_identity, '{{ $database }}_readonly');
        END LOOP;
    END;
    $$;

    DROP EVENT TRIGGER IF EXISTS trigger_auto_grant;
    CREATE EVENT TRIGGER trigger_auto_grant ON ddl_command_end
    WHEN TAG IN ('CREATE SCHEMA')
    EXECUTE PROCEDURE auto_grant_schema_privileges();
    EOT
    {{- end }}

    echo "== assign roles to users"
    psql -v ON_ERROR_STOP=1 --echo-all <<\EOT
    {{- range $database, $d := .Values.databases }}
    {{- range $user, $u := $.Values.users }}
    {{- if has $user $d.roles.admin }}
    GRANT "{{ $database }}_admin" TO "{{ $user }}";
    {{- else }}
    REVOKE "{{ $database }}_admin" FROM "{{ $user }}";
    {{- end }}
    {{- if has $user $d.roles.readonly }}
    GRANT "{{ $database }}_readonly" TO "{{ $user }}";
    {{- else }}
    REVOKE "{{ $database }}_readonly" FROM "{{ $user }}";
    {{- end }}
    {{- end }}
    {{- end }}
    EOT

    echo "== create extensions"
    {{- range $database, $d := .Values.databases }}
    {{- if $d.extensions }}
    psql -v ON_ERROR_STOP=1 --echo-all -d "{{ $database }}" <<\EOT
    {{- range $extension := $d.extensions }}
    CREATE EXTENSION IF NOT EXISTS {{ $extension }};
    {{- end }}
    EOT
    {{- end }}
    {{- end }}