{%- if messages[0]["role"] == "system" %}
    {%- set system_message = messages[0]["content"] %}
    {%- set loop_messages = messages[1:] %}
{%- else %}
    {%- set loop_messages = messages %}
{%- endif %}

{{- bos_token }}
{%- for message in loop_messages %}
    {%- if (message['role'] == 'user') != (loop.index0 % 2 == 0) %}
        {{- raise_exception('After the optional system message, conversation roles must alternate user/assistant/user/assistant/...') }}
    {%- endif %}
    {%- if message["role"] == "user" %}
        {%- if loop.last and system_message is defined %}
            {{- "[INST]" + system_message + "\n" }}
        {%- else %}
            {{- "[INST]" }}
        {%- endif %}
        {%- if message["content"] is not string %}
            {%- for chunk in message["content"] %}
                {%- if chunk["type"] == "text" %}
                    {{- chunk["text"] }}
                {%- elif chunk["type"] == "image" %}
                    {{- "[IMG]" }}
                {%- else %}
                    {{- raise_exception("Unrecognized content type!") }}
                {%- endif %}
            {%- endfor %}
        {%- else %}
            {{- message["content"] }}
        {%- endif %}
        {{- "[/INST]" }}
    {%- elif message["role"] == "assistant" %}
        {{- message["content"] + eos_token}}
    {%- else %}
        {{- raise_exception("Only user and assistant roles are supported, with the exception of an initial optional system message!") }}
    {%- endif %}
{%- endfor %}
