9.Pygit2.ipynb

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    "<span class=\"notebook-slide-start\"/>\n",
    "\n",
    "# Pygit2\n",
    "\n",
    "Este notebook apresenta os seguintes tópicos:\n",
    "\n",
    "- [Pygit2](#Pygit2)\n",
    "- [Exercício 11](#Exerc%C3%ADcio-11)"
   ]
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    "\n",
    "Conseguimos extrair informações do git usando comandos de sistema e parseando os resultados como fizemos anteriormente.\n",
    "\n",
    "Porém, comandos de sistema nem sempre são a alternativa mais rápida e existe um esforço em parsear as informações.\n",
    "\n",
    "Nesta parte do minicurso, falarei da biblioteca `pygit2`, que permite acessar e extrair informações diretamente do repositório."
   ]
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   "source": [
    "Inicialmente, vamos carregar o repositório. <span class=\"notebook-slide-extra\" data-count=\"3\"/>"
   ]
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   "source": [
    "import pygit2"
   ]
  },
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   "source": [
    "%cd sapos\n",
    "repo_path = pygit2.discover_repository(\".\")\n",
    "repo_path"
   ]
  },
  {
   "cell_type": "code",
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   "source": [
    "repo = pygit2.Repository(repo_path)"
   ]
  },
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   "source": [
    "A partir do objeto do repositório, podemos ver em que commit ou tag estamos. <span class=\"notebook-slide-extra\" data-count=\"1\"/>"
   ]
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  {
   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "repo.describe()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Note que o resultado foi a última tag que fizemos checkout, que também é o branch `master`. <span class=\"notebook-slide-scroll\" data-position=\"-1\"/>"
   ]
  },
  {
   "cell_type": "markdown",
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   "source": [
    "Podemos fazer checkout de commits usando a `pygit2`. <span class=\"notebook-slide-extra\" data-count=\"2\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "commit = repo.revparse_single(\"e82315c3ef\")\n",
    "repo.checkout_tree(\n",
    "    commit,\n",
    ")\n",
    "repo.set_head(commit.oid)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "repo.describe()"
   ]
  },
  {
   "cell_type": "markdown",
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   "source": [
    "O checkout de branches é mais simples. <span class=\"notebook-slide-extra\" data-count=\"2\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "master = repo.lookup_branch(\"master\")\n",
    "repo.checkout(master)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "repo.describe()"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Com um objeto de commit, podemos extrair informações dele. <span class=\"notebook-slide-extra\" data-count=\"5\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "commit.oid"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "commit.author.name, commit.author.email"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "commit.commit_time"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "commit.message"
   ]
  },
  {
   "cell_type": "code",
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   "outputs": [],
   "source": [
    "commit.parent_ids"
   ]
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   "source": [
    "Note que por ser um merge, o commit possui dois pais. <span class=\"notebook-slide-scroll\" data-count=\"-1\"/>"
   ]
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  {
   "cell_type": "markdown",
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   "source": [
    "A `pygit2` também possui funções para caminhar pelos commits do repositório. <span class=\"notebook-slide-extra\" data-count=\"1\"/>"
   ]
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   "source": [
    "last_commit = repo[repo.head.target]\n",
    "i = 0\n",
    "for commit in repo.walk(last_commit.id, pygit2.GIT_SORT_TIME):\n",
    "    print(str(commit.id)[:8], commit.message)\n",
    "    i += 1\n",
    "    if i >= 3:\n",
    "        break"
   ]
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   "source": [
    "A forma de caminhar pode variar de acordo com o segundo argumento:\n",
    "    \n",
    "- `GIT_SORT_NONE`: Sem ordem determinada\n",
    "- `GIT_SORT_TOPOLOGICAL`: Ordem topológica - pais antes de filhos\n",
    "- `GIT_SORT_TIME`: Momento do commit\n",
    "- `GIT_SORT_REVERSE`: Ordem inversa\n",
    "\n",
    "Esses argumentos podem ser combinados. Se eu quiser caminhar no inverso da ordem dos commits, posso fazer:\n",
    "```python\n",
    "    GIT_SORT_TIME | GIT_SORT_REVERSE\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "A seguir, usamos essa forma combinada para pegar o primeiro commit do projeto. <span class=\"notebook-slide-extra\" data-count=\"1\"/>"
   ]
  },
  {
   "cell_type": "code",
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   "source": [
    "order = pygit2.GIT_SORT_TIME | pygit2.GIT_SORT_REVERSE\n",
    "it = iter(repo.walk(last_commit.id, order))\n",
    "first_commit = next(it)\n",
    "first_commit.id, first_commit.message"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Podemos usar essa navegação para contar a quantidade de commits no histórico. <span class=\"notebook-slide-extra\" data-count=\"1\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "len(list(repo.walk(last_commit.id)))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Mas note que esse não é o número total de commits do projeto! Ele apenas representa o número de commits no histórico do último commit.\n",
    "\n",
    "Outros commits podem estar em branches ou até mesmo pendurados. <span class=\"notebook-slide-scroll\" data-position=\"-1\"/>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Para pegar todos os commits, precisamos iterar nos objetos do git e selecionar objetos que são commits. <span class=\"notebook-slide-extra\" data-count=\"2\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "commits = []\n",
    "for oid in repo:\n",
    "    obj = repo.get(oid)\n",
    "    if isinstance(obj, pygit2.Commit):\n",
    "        commits.append(obj)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "len(commits)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Agora temos todos os commits. <span class=\"notebook-slide-scroll\" data-position=\"-1\"/>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Em seguida, tentamos descobrir quais são os commits que não estão no histórico do `master`. <span class=\"notebook-slide-extra\" data-count=\"1\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "diff = set(commits) - set(repo.walk(last_commit.id))\n",
    "for commit, _ in zip(diff, range(5)):\n",
    "    print(str(commit.id)[:8], commit.message)\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Quanto listamos os branches no início deste notebook, apenas o `reports` e `bugfixes` não estavam no mesmo commit que o `master`. Desta forma, podemos ver se os commits que não estão no `master` são commits do `reports`, do `bugfixes`, ou se estão pendurados.\n",
    "\n",
    "A seguir verificamos quais commits não são de `reports`. <span class=\"notebook-slide-extra\" data-count=\"1\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "new_diff = diff - set(repo.walk(repo.revparse_single(\"reports\").id))\n",
    "for commit in new_diff:\n",
    "    print(str(commit.id)[:8], commit.message)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Em seguida, verificados se tem algum dos commits que não é de `bugfixes`. <span class=\"notebook-slide-extra\" data-count=\"1\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "new_diff = new_diff - set(repo.walk(repo.revparse_single(\"bugfixes\").id))\n",
    "for commit in new_diff:\n",
    "    print(str(commit.id)[:8], commit.message)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Como não teve nenhum resultado, sabemos que todos os commits que não estão no master são de `reports` ou `bugfixes`. <span class=\"notebook-slide-scroll\" data-position=\"-1\"/>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Outra coisa que podemos fazer com a navegação nos commits é construir uma linha do tempo mostrando quais foram os momentos em que ocorreram mais commits.\n",
    "\n",
    "Começamos calculando quantos dias se passaram desde o primeiro commit até hoje, preparando um array de dias, e inicializando um array de zeros. <span class=\"notebook-slide-extra\" data-count=\"2\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from datetime import datetime\n",
    "first_date = datetime.fromtimestamp(first_commit.commit_time)\n",
    "first_date"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import numpy as np\n",
    "today = datetime.today()\n",
    "delta = today - first_date\n",
    "days = delta.days\n",
    "indexes = np.arange(days)\n",
    "values = np.zeros(days)\n",
    "days"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Navegamos nos commits atualizando values para considerar a contribuição de cada commit novo. <span class=\"notebook-slide-extra\" data-count=\"1\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for commit in commits:\n",
    "    date = datetime.fromtimestamp(commit.commit_time)\n",
    "    delta = date - first_date\n",
    "    delta_index = delta.days\n",
    "    values[delta_index:] += 1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Plotamos o gráfico. <span class=\"notebook-slide-extra\" data-count=\"1\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from math import ceil\n",
    "import matplotlib.pyplot as plt\n",
    "%matplotlib inline\n",
    "\n",
    "labels = [datetime(2011 + i, 1, 1) for i in range(ceil(delta.days / 365))]\n",
    "label_indexes = [(label - first_date).days for label in labels]\n",
    "label_years = [label.year for label in labels]\n",
    "plt.xticks(label_indexes, label_years)\n",
    "plt.plot(indexes, values)\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exercício 11\n",
    "\n",
    "Faça um gráfico mostrando o histórico de contribuições de cada usuário. <span class=\"notebook-slide-extra\" data-count=\"2\"/>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "..."
   ]
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   "cell_type": "code",
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   "source": [
    "bottom = np.zeros(days)\n",
    "legend_color = []\n",
    "legend_text = []\n",
    "...\n",
    "\n",
    "plt.xticks(label_indexes, label_years)\n",
    "plt.xlabel(\"Time\")\n",
    "plt.ylabel(\"Commits\")\n",
    "plt.legend(\n",
    "    legend_color, legend_text,\n",
    "    bbox_to_anchor=(0,1.02,1,0.2), loc=\"lower left\",\n",
    "    mode=\"expand\", borderaxespad=0, ncol=2\n",
    ")\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Continua: [10.Visualizacao.Rica.ipynb](10.Visualizacao.Rica.ipynb)"
   ]
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