terraform {
  required_providers {
    docker = {
      source  = "kreuzwerker/docker"
      version = "~> 3.9"
    }
  }
}

locals {
  persistent = var.environment == "prod"

  # Inject oauth2 token into git URL for private repos
  git_repo_url = (
    var.openresty_git_token != ""
    ? replace(var.openresty_git_repo, "://", "://oauth2:${var.openresty_git_token}@")
    : var.openresty_git_repo
  )

  # Entrypoint for git_clone mode: installs git via apk, clones the pinned ref,
  # then hands off to openresty. The cloned repo must have an 'openresty/' subdirectory
  # containing a valid nginx.conf (used as the -p prefix path).
  git_clone_entrypoint = [
    "/bin/sh", "-c",
    "apk add --no-cache git && git clone --depth 1 --branch '${var.openresty_git_ref}' '${local.git_repo_url}' /tmp/app && exec openresty -g 'daemon off;' -p /tmp/app/openresty"
  ]
}

# ─── Network ──────────────────────────────────────────────────────────────────
# Each app gets its own isolated bridge network. Postgres and Redis are not
# exposed externally; only OpenResty has a published port.

resource "docker_network" "app" {
  name   = "${var.app_name}-network"
  driver = "bridge"
}

# ─── Volumes (prod only) ──────────────────────────────────────────────────────
# In dev mode containers are ephemeral; volumes are created only for prod.

resource "docker_volume" "postgres" {
  count = local.persistent ? 1 : 0
  name  = "${var.app_name}-postgres-data"
}

resource "docker_volume" "redis" {
  count = local.persistent ? 1 : 0
  name  = "${var.app_name}-redis-data"
}

# ─── Images ───────────────────────────────────────────────────────────────────

# Standard OpenResty image — used for bind_mount and git_clone modes.
resource "docker_image" "openresty" {
  count        = var.openresty_source_type != "local_build" ? 1 : 0
  name         = var.openresty_image
  keep_locally = true
}

# Custom-built OpenResty image — used for local_build mode.
# The build context is transferred from the local machine to the remote Docker
# daemon over SSH and built there. Rebuilds are triggered by changes to any
# file in the context directory.
resource "docker_image" "openresty_custom" {
  count        = var.openresty_source_type == "local_build" ? 1 : 0
  name         = "${var.app_name}-openresty:latest"
  keep_locally = true

  build {
    context    = var.openresty_local_build_context
    dockerfile = var.openresty_dockerfile
  }

  triggers = {
    # Rebuild when any file in the build context changes.
    context_hash = sha1(join("", [
      for f in sort(fileset(var.openresty_local_build_context, "**/*")) :
      filesha1("${var.openresty_local_build_context}/${f}")
    ]))
  }
}

resource "docker_image" "postgres" {
  name         = var.postgres_image
  keep_locally = true
}

resource "docker_image" "redis" {
  name         = var.redis_image
  keep_locally = true
}

# ─── PostgreSQL ───────────────────────────────────────────────────────────────

resource "docker_container" "postgres" {
  image   = docker_image.postgres.image_id
  name    = "${var.app_name}-postgres"
  restart = "unless-stopped"

  networks_advanced {
    name = docker_network.app.name
  }

  env = [
    "POSTGRES_DB=${var.db_name}",
    "POSTGRES_USER=${var.db_user}",
    "POSTGRES_PASSWORD=${var.db_password}",
  ]

  dynamic "volumes" {
    for_each = local.persistent ? [1] : []
    content {
      volume_name    = docker_volume.postgres[0].name
      container_path = "/var/lib/postgresql/data"
    }
  }
}

# ─── Redis ────────────────────────────────────────────────────────────────────

resource "docker_container" "redis" {
  image   = docker_image.redis.image_id
  name    = "${var.app_name}-redis"
  restart = "unless-stopped"

  networks_advanced {
    name = docker_network.app.name
  }

  dynamic "volumes" {
    for_each = local.persistent ? [1] : []
    content {
      volume_name    = docker_volume.redis[0].name
      container_path = "/data"
    }
  }
}

# ─── OpenResty ────────────────────────────────────────────────────────────────

resource "docker_container" "openresty" {
  image = (
    var.openresty_source_type == "local_build"
    ? docker_image.openresty_custom[0].image_id
    : docker_image.openresty[0].image_id
  )
  name    = "${var.app_name}-openresty"
  restart = "unless-stopped"

  networks_advanced {
    name = docker_network.app.name
  }

  ports {
    internal = 80
    external = var.openresty_external_port
  }

  # bind_mount: mount a pre-existing directory from the remote host.
  # The directory must contain a valid nginx.conf and any Lua files.
  dynamic "volumes" {
    for_each = var.openresty_source_type == "bind_mount" ? [1] : []
    content {
      host_path      = var.openresty_remote_config_path
      container_path = "/usr/local/openresty/nginx/conf"
      read_only      = true
    }
  }

  # git_clone: override the container entrypoint to clone the repo and start openresty.
  # The base image must support apk (Alpine). The cloned repo must have an openresty/
  # subdirectory with nginx.conf.
  entrypoint = var.openresty_source_type == "git_clone" ? local.git_clone_entrypoint : null

  # Expose service connection info as env vars so Lua code can use them via os.getenv().
  env = [
    "APP_NAME=${var.app_name}",
    "POSTGRES_HOST=${var.app_name}-postgres",
    "POSTGRES_DB=${var.db_name}",
    "POSTGRES_USER=${var.db_user}",
    "POSTGRES_PASSWORD=${var.db_password}",
    "REDIS_HOST=${var.app_name}-redis",
  ]

  depends_on = [
    docker_container.postgres,
    docker_container.redis,
  ]
}