neiam /gitgud

defmodule GitGud.Repo.Migrations.CreateGitCaches do
  use Ecto.Migration

  def change do
    # Mutable: current state of refs. Authoritative storage is on-disk,
    # but the UI reads here.
    create table(:git_refs, primary_key: false) do
      add :repository_id, references(:repositories, on_delete: :delete_all),
        null: false,
        primary_key: true

      add :name, :string, null: false, primary_key: true
      add :target_sha, :binary, null: false
      add :peeled_sha, :binary
      add :ref_type, :string, null: false, default: "branch"

      timestamps(type: :utc_datetime, updated_at: :updated_at, inserted_at: false)
    end

    create index(:git_refs, [:repository_id, :ref_type])

    # Immutable, content-addressed. SHA = raw 20-byte sha1.
    create table(:git_commits, primary_key: false) do
      add :repository_id, references(:repositories, on_delete: :delete_all),
        null: false,
        primary_key: true

      add :sha, :binary, null: false, primary_key: true
      add :tree_sha, :binary, null: false
      add :parent_shas, {:array, :binary}, null: false, default: []
      add :author_name, :string
      add :author_email, :string
      add :authored_at, :utc_datetime
      add :committer_name, :string
      add :committer_email, :string
      add :committed_at, :utc_datetime
      add :message, :text
      # commit-graph generation number; supports paginated revwalk
      add :generation, :integer

      add :inserted_at, :utc_datetime, null: false, default: fragment("now()")
    end

    create index(:git_commits, [:repository_id, :committed_at])
    create index(:git_commits, [:repository_id, :author_email])

    # Tree entries stored as a single jsonb blob per tree. Keeps reads to
    # one row per directory listing.
    create table(:git_trees, primary_key: false) do
      add :repository_id, references(:repositories, on_delete: :delete_all),
        null: false,
        primary_key: true

      add :sha, :binary, null: false, primary_key: true
      # [{name, mode, type, sha, size}, ...]
      add :entries, :map, null: false

      add :inserted_at, :utc_datetime, null: false, default: fragment("now()")
    end

    # Cheap metadata about blobs. Bytes themselves stay in the git
    # object store on disk (or LFS in Garage).
    create table(:git_blob_meta, primary_key: false) do
      add :repository_id, references(:repositories, on_delete: :delete_all),
        null: false,
        primary_key: true

      add :sha, :binary, null: false, primary_key: true
      add :size, :bigint, null: false
      add :mime, :string
      add :is_binary, :boolean, null: false, default: false
      add :line_count, :integer
      add :detected_language, :string

      add :inserted_at, :utc_datetime, null: false, default: fragment("now()")
    end

    # Per-commit diff summary for fast "x files +y -z" rendering.
    create table(:git_commit_diffstats, primary_key: false) do
      add :repository_id, references(:repositories, on_delete: :delete_all),
        null: false,
        primary_key: true

      add :sha, :binary, null: false, primary_key: true
      add :files_changed, :integer, null: false, default: 0
      add :insertions, :integer, null: false, default: 0
      add :deletions, :integer, null: false, default: 0
      # Touched paths kept for "files in this commit" listing and for
      # cheap path-filtered log queries.
      add :paths, {:array, :string}, null: false, default: []

      add :inserted_at, :utc_datetime, null: false, default: fragment("now()")
    end

    # LRU-evictable render cache. kind = markdown | highlight | plain.
    # renderer_version lets us invalidate on MDEx / highlighter upgrades.
    create table(:git_renders, primary_key: false) do
      add :repository_id, references(:repositories, on_delete: :delete_all),
        null: false,
        primary_key: true

      add :blob_sha, :binary, null: false, primary_key: true
      add :kind, :string, null: false, primary_key: true
      add :renderer_version, :integer, null: false, primary_key: true
      add :body, :text, null: false
      add :touched_at, :utc_datetime, null: false, default: fragment("now()")

      add :inserted_at, :utc_datetime, null: false, default: fragment("now()")
    end

    create index(:git_renders, [:repository_id, :touched_at])
  end
end