#!/usr/bin/env bash
set -euo pipefail

ROOT="$(cd "$(dirname "$0")/.." && pwd)"
CONFIG_PATH="${CONTINUITY_PROVIDER_CONFIG:-$ROOT/build/system/continuity_provider.json}"
COMMAND="${1:-status}"
ARG1="${2:-}"
ARG2="${3:-}"

if [ ! -f "$CONFIG_PATH" ]; then
  echo "continuity provider config not found: $CONFIG_PATH" >&2
  exit 1
fi

json_config() {
  jq "$1" "$CONFIG_PATH"
}

config_value() {
  jq -r "$1" "$CONFIG_PATH"
}

external_base_url() {
  config_value '.external.base_url'
}

external_url() {
  local path="$1"
  printf '%s%s' "$(external_base_url)" "$path"
}

api_key_header() {
  config_value '.external.api_key_header'
}

tenant_header() {
  config_value '.external.tenant_header'
}

api_key_value() {
  if [ -n "${CONTINUITY_PROVIDER_API_KEY:-}" ]; then
    printf '%s' "$CONTINUITY_PROVIDER_API_KEY"
  else
    config_value '.external.api_key_default'
  fi
}

tenant_value() {
  if [ -n "${CONTINUITY_PROVIDER_TENANT:-}" ]; then
    printf '%s' "$CONTINUITY_PROVIDER_TENANT"
  else
    config_value '.external.tenant_default'
  fi
}

health_ok() {
  local body
  body="$(curl -fsS "$(external_url "$(config_value '.external.health_path')")" 2>/dev/null || true)"
  [ "$body" = "ok" ]
}

curl_json() {
  local method="$1"
  local url="$2"
  local data="${3:-}"
  if [ -n "$data" ]; then
    curl -fsS -X "$method" \
      -H 'content-type: application/json' \
      -H "$(api_key_header): $(api_key_value)" \
      -H "$(tenant_header): $(tenant_value)" \
      -d "$data" \
      "$url"
  else
    curl -fsS -X "$method" \
      -H "$(api_key_header): $(api_key_value)" \
      -H "$(tenant_header): $(tenant_value)" \
      "$url"
  fi
}

fallback_pointer_path() {
  local rel
  rel="$(config_value '.fallback.latest_pointer_path')"
  printf '%s/%s' "$ROOT" "$rel"
}

fallback_status() {
  local pointer_path
  pointer_path="$(fallback_pointer_path)"
  if [ ! -f "$pointer_path" ]; then
    jq -n '{provider:"local_fallback", available:false}'
    return 0
  fi
  jq -n \
    --argjson pointer "$(cat "$pointer_path")" \
    '{
      provider:"local_fallback",
      available:true,
      continuity_version_id:$pointer.continuity_version_id,
      predecessor_id:$pointer.predecessor_id,
      default_surface:$pointer.default_surface,
      surface_ids:$pointer.surface_ids,
      endpoint_ids:$pointer.endpoint_ids,
      lineage_path:$pointer.lineage_path,
      surface_registry_path:$pointer.surface_registry_path,
      status:$pointer.status
    }'
}

fallback_surfaces() {
  local pointer_path registry_path
  pointer_path="$(fallback_pointer_path)"
  if [ ! -f "$pointer_path" ]; then
    jq -n '{provider:"local_fallback", items:[]}'
    return 0
  fi
  registry_path="$(jq -r '.surface_registry_path' "$pointer_path")"
  registry_path="$ROOT/$registry_path"
  if [ ! -f "$registry_path" ]; then
    jq -n '{provider:"local_fallback", items:[]}'
    return 0
  fi
  jq -n \
    --argjson registry "$(cat "$registry_path")" \
    '{
      provider:"local_fallback",
      items: [
        $registry.surfaces[] | {
          surface_id:.id,
          version_id:$registry.continuity_version_id,
          activated:(.id == $registry.default_surface),
          title:.title,
          purpose:.purpose
        }
      ]
    }'
}

fallback_lineage() {
  local version_id="$1"
  local pointer_path lineage_path
  pointer_path="$(fallback_pointer_path)"
  if [ ! -f "$pointer_path" ]; then
    jq -n '{provider:"local_fallback", available:false}'
    return 0
  fi
  lineage_path="$(jq -r '.lineage_path' "$pointer_path")"
  lineage_path="$ROOT/$lineage_path"
  if [ ! -f "$lineage_path" ]; then
    jq -n '{provider:"local_fallback", available:false}'
    return 0
  fi
  jq -n \
    --arg requested_version "$version_id" \
    --argjson lineage "$(cat "$lineage_path")" \
    'if $requested_version != "" and $requested_version != $lineage.continuity_version_id
      then {provider:"local_fallback", available:false}
      else {
        provider:"local_fallback",
        available:true,
        version_id:$lineage.continuity_version_id,
        predecessor:$lineage.predecessor_id,
        receipts_required:$lineage.receipts_required,
        verified:false,
        promoted:false,
        manifest_path:$lineage.manifest_path
      }
    end'
}

instantiate_payload() {
  local version_id="$1"
  local predecessor="$2"
  if [ -n "$version_id" ] && [ -f "$version_id" ]; then
    predecessor="$(jq -r '.predecessor_id // .predecessor // "hv-conversational-control-plane-v0"' "$version_id")"
    version_id="$(jq -r '.continuity_version_id // .version_id // "hv-continuity-control-plane-v1"' "$version_id")"
  fi
  jq -n \
    --arg version_id "${version_id:-hv-continuity-control-plane-v1}" \
    --arg predecessor "${predecessor:-hv-conversational-control-plane-v0}" \
    '{
      goal:"Instantiate continuity runtime",
      ops:[
        {
          op:"instantiate_continuity_runtime",
          args:{
            version_id:$version_id,
            predecessor:$predecessor,
            receipts_required:["r-chat-history-graph-20260408","r-chat-history-pass-20260408"],
            receipts_ready:["r-chat-history-graph-20260408","r-chat-history-pass-20260408"],
            promote_if_verified:true
          }
        }
      ]
    }'
}

case "$COMMAND" in
  status)
    if health_ok; then
      curl_json GET "$(external_url "$(config_value '.external.versions_path')")" \
        | jq '{provider:"external_nextgen", available:true, items:.items}'
    else
      fallback_status
    fi
    ;;
  surfaces)
    if health_ok; then
      curl_json GET "$(external_url "$(config_value '.external.surfaces_path')")" \
        | jq '{provider:"external_nextgen", items:.items}'
    else
      fallback_surfaces
    fi
    ;;
  lineage)
    if [ -z "$ARG1" ]; then
      echo "usage: continuity_provider.sh lineage <version_id>" >&2
      exit 1
    fi
    if health_ok; then
      curl_json GET "$(external_url "$(config_value '.external.versions_path')")/$ARG1/lineage" \
        | jq '. + {provider:"external_nextgen"}'
    else
      fallback_lineage "$ARG1"
    fi
    ;;
  activate)
    if [ -z "$ARG1" ]; then
      echo "usage: continuity_provider.sh activate <surface_id> [version_id]" >&2
      exit 1
    fi
    if health_ok; then
      curl_json POST \
        "$(external_url "$(config_value '.external.surfaces_path')")/$ARG1/activate" \
        "$(jq -n --arg version_id "${ARG2:-hv-continuity-control-plane-v1}" '{version_id:$version_id}')"
    else
      echo "activate is not supported in local fallback mode" >&2
      exit 1
    fi
    ;;
  instantiate)
    if health_ok; then
      curl_json POST \
        "$(external_url "$(config_value '.external.nextgen_path')")" \
        "$(instantiate_payload "$ARG1" "$ARG2")"
    else
      "$ROOT/runtime/materialize_continuity_slice.sh" "${ARG1:-$ROOT/runtime/examples/continuity_v1_manifest.json}"
    fi
    ;;
  *)
    echo "unsupported command: $COMMAND" >&2
    exit 1
    ;;
esac