# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Nit object oriented interface to [Github api](https://developer.github.com/v3/).
#
# This modules reifies Github API elements as Nit classes.
#
# For most use-cases you need to use the `GithubAPI` client.
module api

intrude import json::serialization_read

import base64
import curl
import json

# Client to Github API
#
# To access the API you need an instance of a `GithubAPI` client.
#
# ~~~nitish
# # Get Github authentification token.
# var token = get_github_oauth
# assert not token.is_empty
#
# # Init the client.
# var api = new GithubAPI(token)
# ~~~
#
# The API client allows you to get Github API entities.
#
# ~~~nitish
# var repo = api.get_repo("nitlang/nit")
# assert repo != null
# assert repo.name == "nit"
#
# var user = api.get_user("Morriar")
# assert user != null
# assert user.login == "Morriar"
# ~~~
class GithubAPI

	# Github API OAuth token
	#
	# To access your private ressources, you must
	# [authenticate](https://developer.github.com/guides/basics-of-authentication/).
	#
	# For client applications, Github recommands to use the
	# [OAuth tokens](https://developer.github.com/v3/oauth/) authentification method.
	#
	#
	#
	# Be aware that there is [rate limits](https://developer.github.com/v3/rate_limit/)
	# associated to the key.
	var auth: nullable String = null is optional

	# User agent used for HTTP requests.
	#
	# Default is `nit_github_api`.
	#
	# See <https://developer.github.com/v3/#user-agent-required>
	var user_agent: String = "nit_github_api" is optional

	# Headers to use on all requests
	fun new_headers: HeaderMap do
		var map = new HeaderMap
		var auth = self.auth
		if auth != null then
			map["Authorization"] = "token {auth}"
		end
		map["User-Agent"] = user_agent
		# FIXME remove when projects and team are no more in beta
		map["Accept"] = "application/vnd.github.inertia-preview+json"
		map["Accept"] = "application/vnd.github.hellcat-preview+json"
		return map
	end

	# Github API base url.
	#
	# Default is `https://api.github.com` and should not be changed.
	var api_url = "https://api.github.com"

	# Send a HTTPRequest to the Github API
	fun send(method, path: String, headers: nullable HeaderMap, body: nullable String): nullable String do
		last_error = null
		path = sanitize_uri(path)
		var uri = "{api_url}{path}"
		var request = new CurlHTTPRequest(uri)
		request.method = method
		request.user_agent = user_agent
		request.headers = headers or else self.new_headers
		request.body = body
		return check_response(uri, request.execute)
	end

	private fun check_response(uri: String, response: CurlResponse): nullable String do
		if response isa CurlResponseSuccess then
			was_error = false
			return response.body_str
		else if response isa CurlResponseFailed then
			last_error = new GithubAPIError(
				response.error_msg,
				response.error_code,
				uri
			)
			was_error = true
			return null
		else abort
	end

	# Deserialize an object
	fun deserialize(string: nullable Serializable): nullable Object do
		if string == null then return null
		var deserializer = new GithubDeserializer(string.to_s)
		var res = deserializer.deserialize
		if deserializer.errors.not_empty then
			was_error = true
			last_error = new GithubDeserializerErrors("Deserialization failed", deserializer.errors)
			return null
		else if res isa GithubError then
			was_error = true
			last_error = res
			return null
		end
		was_error = false
		return res
	end

	# Escape `uri` in an acceptable format for Github.
	private fun sanitize_uri(uri: String): String do
		# TODO better URI escape.
		return uri.replace(" ", "%20")
	end

	# Last error occured during Github API communications.
	var last_error: nullable Error = null is public writable

	# Does the last request provoqued an error?
	var was_error = false is protected writable

	# Execute a GET request on Github API.
	#
	# This method returns a deserialized result.
	#
	# For raw data see `send`.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var obj = api.get("/repos/nitlang/nit")
	# assert obj isa Repo
	# assert obj.name == "nit"
	# ~~~
	#
	# Returns `null` in case of `error`.
	#
	# ~~~nitish
	# obj = api.get("/foo/bar/baz")
	# assert obj == null
	# assert api.was_error
	# assert api.last_error isa GithubError
	# ~~~
	fun get(path: String, headers: nullable HeaderMap, data: nullable String): nullable Object do
		return deserialize(send("GET", path, headers, data))
	end

	# Get the Github logged user from `auth` token.
	#
	# Loads the `User` from the API or returns `null` if the user cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var user = api.get_auth_user
	# assert user.login == "Morriar"
	# ~~~
	fun get_auth_user: nullable User do
		return get("/user").as(nullable User)
	end

	# Get the Github user with `login`
	#
	# Loads the `User` from the API or returns `null` if the user cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var user = api.get_user("Morriar")
	# print user or else "null"
	# assert user.login == "Morriar"
	# ~~~
	fun get_user(login: String): nullable User do
		return get("/users/{login}").as(nullable User)
	end

	# Get the Github repo with `full_name`.
	#
	# Loads the `Repo` from the API or returns `null` if the repo cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var repo = api.get_repo("nitlang/nit")
	# assert repo.name == "nit"
	# assert repo.owner.login == "nitlang"
	# assert repo.default_branch == "master"
	# ~~~
	fun get_repo(repo_slug: String): nullable Repo do
		return get("/repos/{repo_slug}").as(nullable Repo)
	end

	# List of repo branches.
	#
	# Pagination:
	#	* `page`: page to fetch (default: 1)
	#	* `per_page`: number of branches by page (default: 30)
	fun get_repo_branches(repo_slug: String, page, per_page: nullable Int): Array[Branch] do
		return new GithubArray[Branch].from(get(
			"/repos/{repo_slug}/branches?{pagination(page, per_page)}"))
	end

	# List of issues associated with their ids.
	fun get_repo_issues(repo_slug: String, page, per_page: nullable Int): Array[Issue] do
		return new GithubArray[Issue].from(get(
			"/repos/{repo_slug}/issues?{pagination(page, per_page)}"))
	end

	# Search issues in this repo form an advanced query.
	#
	# Example:
	#
	# ~~~nitish
	# var issues = repo.search_issues("is:open label:need_review")
	# ~~~
	#
	# See <https://developer.github.com/v3/search/#search-issues>.
	fun search_repo_issues(repo_slug: String, query: String, page, per_page: nullable Int): nullable SearchResults do
		return get("/search/issues?q={query} repo:{repo_slug}&{pagination(page, per_page)}").as(nullable SearchResults)
	end

	# List of labels associated with their names.
	fun get_repo_labels(repo_slug: String, page, per_page: nullable Int): Array[Label] do
		return new GithubArray[Label].from(get(
			"/repos/{repo_slug}/labels?{pagination(page, per_page)}"))
	end

	# List of milestones associated with their ids.
	fun get_repo_milestones(repo_slug: String, page, per_page: nullable Int): Array[Milestone] do
		return new GithubArray[Milestone].from(get(
			"/repos/{repo_slug}/milestones?{pagination(page, per_page)}"))
	end

	# List of pull-requests associated with their ids.
	#
	# Implementation notes: because PR numbers are not consecutive,
	# PR are loaded from pages.
	# See: https://developer.github.com/v3/pulls/#list-pull-requests
	fun get_repo_pulls(repo_slug: String, page, per_page: nullable Int): Array[PullRequest] do
		return new GithubArray[PullRequest].from(get(
			"/repos/{repo_slug}/pulls?{pagination(page, per_page)}"))
	end

	# List of contributor related statistics.
	fun get_repo_contrib_stats(repo_slug: String): Array[ContributorStats] do
		return new GithubArray[ContributorStats].from(get("/repos/{repo_slug}/stats/contributors"))
	end

	# Get the Github branch with `name`.
	#
	# Returns `null` if the branch cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var repo = api.get_repo("nitlang/nit")
	# assert repo != null
	# var branch = api.get_branch(repo, "master")
	# assert branch.name == "master"
	# assert branch.commit isa Commit
	# ~~~
	fun get_branch(repo_slug: String, name: String): nullable Branch do
		return get("/repos/{repo_slug}/branches/{name}").as(nullable Branch)
	end

	# Get the Github commit with `sha`.
	#
	# Returns `null` if the commit cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var repo = api.get_repo("nitlang/nit")
	# assert repo != null
	# var commit = api.get_commit(repo, "64ce1f")
	# assert commit isa Commit
	# ~~~
	fun get_commit(repo_slug: String, sha: String): nullable Commit do
		return get("/repos/{repo_slug}/commits/{sha}").as(nullable Commit)
	end

	# Get the status of a commit
	#
	# The status holds the result of each check ran on a commit like CI, reviews etc.
	fun get_commit_status(repo_slug: String, sha: String): nullable CommitStatus do
		return get("/repos/{repo_slug}/commits/{sha}/status").as(nullable CommitStatus)
	end

	# Get the Github issue #`number`.
	#
	# Returns `null` if the issue cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var repo = api.get_repo("nitlang/nit")
	# assert repo != null
	# var issue = api.get_issue(repo, 1)
	# assert issue.title == "Doc"
	# ~~~
	fun get_issue(repo_slug: String, number: Int): nullable Issue do
		return get("/repos/{repo_slug}/issues/{number}").as(nullable Issue)
	end

	# List of event on this issue.
	fun get_issue_comments(repo_slug: String, issue_number: Int, page, per_page: nullable Int): Array[IssueComment] do
		return new GithubArray[IssueComment].from(get(
			"/repos/{repo_slug}/issues/{issue_number}/comments?{pagination(page, per_page)}"))
	end

	# List of events on this issue.
	fun get_issue_events(repo_slug: String, issue_number: Int, page, per_page: nullable Int): Array[IssueEvent] do
		return new GithubArray[IssueEvent].from(get(
			"/repos/{repo_slug}/issues/{issue_number}/events?{pagination(page, per_page)}"))
	end

	# Get the Github pull request #`number`.
	#
	# Returns `null` if the pull request cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var repo = api.get_repo("nitlang/nit")
	# assert repo != null
	# var pull = api.get_pull(repo, 1)
	# assert pull.title == "Doc"
	# assert pull.user.login == "Morriar"
	# ~~~
	fun get_pull(repo_slug: String, number: Int): nullable PullRequest do
		return get("/repos/{repo_slug}/pulls/{number}").as(nullable PullRequest)
	end

	# List of comments on a pull request
	fun get_pull_comments(repo_slug: String, pull_number: Int, page, per_page: nullable Int): Array[PullComment] do
		return new GithubArray[PullComment].from(get(
			"/repos/{repo_slug}/pulls/{pull_number}/comments?{pagination(page, per_page)}"))
	end

	# Get a specific pull request comment
	fun get_pull_comment(repo_slug: String, id: Int): nullable PullComment do
		return get("/repos/{repo_slug}/pulls/comments/{id}").as(nullable PullComment)
	end

	# Get the Github label with `name`.
	#
	# Returns `null` if the label cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var repo = api.get_repo("nitlang/nit")
	# assert repo != null
	# var labl = api.get_label(repo, "ok_will_merge")
	# assert labl != null
	# ~~~
	fun get_label(repo_slug: String, name: String): nullable Label do
		return get("/repos/{repo_slug}/labels/{name}").as(nullable Label)
	end

	# Get the Github milestone with `id`.
	#
	# Returns `null` if the milestone cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var repo = api.get_repo("nitlang/nit")
	# assert repo != null
	# var stone = api.get_milestone(repo, 4)
	# assert stone.title == "v1.0prealpha"
	# ~~~
	fun get_milestone(repo_slug: String, id: Int): nullable Milestone do
		return get("/repos/{repo_slug}/milestones/{id}").as(nullable Milestone)
	end

	# Get the Github issue event with `id`.
	#
	# Returns `null` if the event cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var repo = api.get_repo("nitlang/nit")
	# assert repo isa Repo
	# var event = api.get_issue_event(repo, 199674194)
	# assert event isa IssueEvent
	# assert event.actor.login == "privat"
	# assert event.event == "labeled"
	# assert event.labl isa Label
	# assert event.labl.name == "need_review"
	# ~~~
	fun get_issue_event(repo_slug: String, id: Int): nullable IssueEvent do
		return get("/repos/{repo_slug}/issues/events/{id}").as(nullable IssueEvent)
	end

	# Get the Github commit comment with `id`.
	#
	# Returns `null` if the comment cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var repo = api.get_repo("nitlang/nit")
	# assert repo != null
	# var comment = api.get_commit_comment(repo, 8982707)
	# assert comment.user.login == "Morriar"
	# assert comment.body == "For testing purposes...\n"
	# assert comment.commit_id == "7eacb86d1e24b7e72bc9ac869bf7182c0300ceca"
	# ~~~
	fun get_commit_comment(repo_slug: String, id: Int): nullable CommitComment do
		return get("/repos/{repo_slug}/comments/{id}").as(nullable CommitComment)
	end

	# Get the Github issue comment with `id`.
	#
	# Returns `null` if the comment cannot be found.
	#
	# ~~~nitish
	# var api = new GithubAPI(get_github_oauth)
	# var repo = api.get_repo("nitlang/nit")
	# assert repo != null
	# var comment = api.get_issue_comment(repo, 6020149)
	# assert comment.user.login == "privat"
	# assert comment.created_at.to_s == "2012-05-30T20:16:54Z"
	# assert comment.issue_number == 10
	# ~~~
	fun get_issue_comment(repo_slug: String, id: Int): nullable IssueComment do
		return get("/repos/{repo_slug}/issues/comments/{id}").as(nullable IssueComment)
	end

	private fun pagination(page, per_page: nullable Int): String do
		return "page={page or else 1}&per_page={per_page or else 30}"
	end
end

# Return deserialization as an array of E
#
# Non-subtypes will be ignored.
private class GithubArray[E]
	super Array[E]

	# Create `self` from an Array of objects
	#
	# Objects non-subtyping E will be ignored.
	init from(res: nullable Object) do
		if not res isa Array[Object] then return
		for obj in res do
			if obj isa E then add obj
		end
	end
end

# An Error returned by GithubAPI
class GithubError
	super Error
end

# An Error returned by https://api.github.com
#
# Anything that can occurs when sending request to the API:
# * Can't connect to API
# * Ressource not found
# * Validation error
# * ...
class GithubAPIError
	super GithubError

	# Status code obtained
	var status_code: Int

	# URI that returned the error
	var requested_uri: String
end

# An Error returned while deserializing objects from the API
class GithubDeserializerErrors
	super GithubError

	# Errors returned by the deserizalization process
	var deserizalization_errors: Array[Error]
end

# A Github user
#
# Provides access to [Github user data](https://developer.github.com/v3/users/).
# Should be accessed from `GithubAPI::get_user`.
class User
	super GitUser
	serialize

	# Github login.
	var login: String is writable

	# Avatar image url for this user.
	var avatar_url: nullable String is writable

	# User public name if any.
	var name: nullable String is writable

	# User public email if any.
	var email: nullable String is writable

	# User public blog if any.
	var blog: nullable String is writable
end

# A Github repository.
#
# Provides access to [Github repo data](https://developer.github.com/v3/repos/).
# Should be accessed from `GithubAPI::get_repo`.
class Repo
	serialize

	# Repo full name on Github.
	var full_name: String is writable

	# Repo short name on Github.
	var name: String is writable

	# Get the repo owner.
	var owner: User is writable

	# Repo default branch name.
	var default_branch: nullable String = null is optional, writable
end

# A Github branch.
#
# Should be accessed from `GithubAPI::get_branch`.
#
# See <https://developer.github.com/v3/repos/#list-branches>.
class Branch
	serialize

	# Branch name.
	var name: String is writable

	# Get the last commit of `self`.
	var commit: Commit is writable
end

# A Github commit.
#
# Should be accessed from `GithubAPI::get_commit`.
#
# See <https://developer.github.com/v3/repos/commits/>.
class Commit
	serialize

	# Commit SHA.
	var sha: String is writable

	# Parent commits of `self`.
	var parents: nullable Array[Commit] = null is writable

	# Author of the commit.
	var author: nullable GitUser is writable

	# Committer of the commit.
	var committer: nullable GitUser is writable

	# Authoring date as String.
	var author_date: nullable String is writable

	# Commit date as String.
	var commit_date: nullable String is writable

	# List files staged in this commit.
	var files: nullable Array[GithubFile] = null is optional, writable

	# Commit message.
	var message: nullable String is writable

	# Git commit representation linked to this commit.
	var commit: nullable GitCommit
end

# A Git Commit representation
class GitCommit
	serialize

	# Commit SHA.
	var sha: nullable String is writable

	# Parent commits of `self`.
	var parents: nullable Array[GitCommit] = null is writable

	# Author of the commit.
	var author: nullable GitUser is writable

	# Committer of the commit.
	var committer: nullable GitUser is writable

	# Commit message.
	var message: nullable String is writable
end

# Git user authoring data
class GitUser
	serialize

	# Authoring date.
	var date: nullable String = null is writable
end

# A Github issue.
#
# Should be accessed from `GithubAPI::get_issue`.
#
# See <https://developer.github.com/v3/issues/>.
class Issue
	serialize

	# Issue Github ID.
	var number: Int is writable

	# Issue id.
	var id: nullable Int is writable

	# Issue title.
	var title: String is writable

	# User that created this issue.
	var user: nullable User is writable

	# List of labels on this issue associated to their names.
	var labels: nullable Array[Label] is writable

	# State of the issue on Github.
	var state: String is writable

	# Is the issue locked?
	var locked: nullable Bool is writable

	# Assigned `User` (if any).
	var assignee: nullable User is writable

	# `Milestone` (if any).
	var milestone: nullable Milestone is writable

	# Number of comments on this issue.
	var comments: nullable Int is writable

	# Creation time as String.
	var created_at: String is writable

	# Last update time as String (if any).
	var updated_at: nullable String is writable

	# Close time as String (if any).
	var closed_at: nullable String is writable

	# Full description of the issue.
	var body: nullable String is writable

	# User that closed this issue (if any).
	var closed_by: nullable User is writable

	# Is this issue linked to a pull request?
	var is_pull_request: Bool = false is writable
end

# A Github pull request.
#
# Should be accessed from `GithubAPI::get_pull`.
#
# PullRequest are basically Issues with more data.
# See <https://developer.github.com/v3/pulls/>.
class PullRequest
	super Issue
	serialize

	# Merge time as String (if any).
	var merged_at: nullable String is writable

	# Merge commit SHA.
	var merge_commit_sha: nullable String is writable

	# Count of comments made on the pull request diff.
	var review_comments: nullable Int is writable

	# Pull request head (can be a commit SHA or a branch name).
	var head: PullRef is writable

	# Pull request base (can be a commit SHA or a branch name).
	var base: PullRef is writable

	# Is this pull request merged?
	var merged: nullable Bool is writable

	# Is this pull request mergeable?
	var mergeable: nullable Bool is writable

	# Mergeable state of this pull request.
	#
	# See <https://developer.github.com/v3/pulls/#list-pull-requests>.
	var mergeable_state: nullable String is writable

	# User that merged this pull request (if any).
	var merged_by: nullable User is writable

	# Count of commits in this pull request.
	var commits: nullable Int is writable

	# Added line count.
	var additions: nullable Int is writable

	# Deleted line count.
	var deletions: nullable Int is writable

	# Changed files count.
	var changed_files: nullable Int is writable

	# URL to patch file
	var patch_url: nullable String is writable
end

# A pull request reference (used for head and base).
class PullRef
	serialize

	# Label pointed by `self`.
	var labl: String is writable, serialize_as("label")

	# Reference pointed by `self`.
	var ref: String is writable

	# Commit SHA pointed by `self`.
	var sha: String is writable

	# User pointed by `self`.
	var user: User is writable

	# Repo pointed by `self` (if any).
	#
	# A `null` value means the `repo` was deleted.
	var repo: nullable Repo is writable
end

# A Github label.
#
# Should be accessed from `GithubAPI::get_label`.
#
# See <https://developer.github.com/v3/issues/labels/>.
class Label
	serialize

	# Label name.
	var name: String is writable

	# Label color code.
	var color: String is writable
end

# A Github milestone.
#
# Should be accessed from `GithubAPI::get_milestone`.
#
# See <https://developer.github.com/v3/issues/milestones/>.
class Milestone
	serialize

	# The milestone id on Github.
	var number: nullable Int = null is writable

	# Milestone title.
	var title: String is writable

	# Milestone long description.
	var description: nullable String is writable

	# Count of opened issues linked to this milestone.
	var open_issues: nullable Int = null is writable

	# Count of closed issues linked to this milestone.
	var closed_issues: nullable Int = null is writable

	# Milestone state.
	var state: nullable String is writable

	# Creation time as String.
	var created_at: nullable String is writable

	# User that created this milestone.
	var creator: nullable User is writable

	# Due time as String (if any).
	var due_on: nullable String is writable

	# Last update time as String (if any).
	var updated_at: nullable String is writable

	# Close time as String (if any).
	var closed_at: nullable String is writable
end

# A Github comment
#
# There is two kinds of comments:
#
# * `CommitComment` are made on a commit page.
# * `IssueComment` are made on an issue or pull request page.
# * `PullComment` are made on the diff associated to a pull request.
abstract class Comment
	serialize

	# Identifier of this comment.
	var id: Int is writable

	# User that made this comment.
	var user: User is writable

	# Creation time as String.
	var created_at: String is writable

	# Last update time as String (if any).
	var updated_at: nullable String is writable

	# Comment body text.
	var body: String is writable

	# Does the comment contain an acknowledgement (+1)
	fun is_ack: Bool do
		return body.has("\\+1\\b".to_re) or body.has(":+1:") or body.has(":shipit:")
	end
end

# A comment made on a commit.
class CommitComment
	super Comment
	serialize

	# Commented commit.
	var commit_id: String is writable

	# Position of the comment on the line.
	var position: nullable Int is writable

	# Line of the comment.
	var line: nullable Int is writable

	# Path of the commented file.
	var path: nullable String is writable
end

# Status of a commit
#
# Can contain sub-status for reviews, CI etc.
class CommitStatus
	serialize

	# Global state of this commit
	var state: nullable String = null is optional, writable

	# Sha of the commit this status is for
	var sha: nullable String = null is optional, writable

	# Repository the commit belongs to
	var repository: nullable Repo = null is optional, writable

	# All sub statuses (one for each check)
	var statuses = new Array[RepoStatus] is optional, writable

	# Total count of sub statuses
	var total_count: nullable Int = null is optional, writable
end

# Sub status of a CommitStatus
#
# Represents a check applied to a commit (reviews, CI, ...).
class RepoStatus
	serialize

	# State of this check
	var state: nullable String = null is optional, writable

	# Description of this check
	var description: nullable String = null is optional, writable

	# External URL
	var target_url: nullable String = null is optional, writable

	# Context this status is related to
	#
	# Used to hold the name of the check applied.
	var context: nullable String = null is optional, writable

	# Date when this status was created
	var created_at: nullable String = null is optional, writable

	# Last date this status was updated
	var updated_at: nullable String = null is optional, writable
end

# Comments made on Github issue and pull request pages.
#
# Should be accessed from `GithubAPI::get_issue_comment`.
#
# See <https://developer.github.com/v3/issues/comments/>.
class IssueComment
	super Comment
	serialize

	# Issue that contains `self`.
	fun issue_number: Int do return issue_url.split("/").last.to_i

	# Link to the issue document on API.
	var issue_url: String is writable
end

# Comments made on Github pull request diffs.
#
# Should be accessed from `GithubAPI::get_diff_comment`.
#
# See <https://developer.github.com/v3/pulls/comments/>.
class PullComment
	super Comment
	serialize

	# Pull request that contains `self`.
	fun pull_number: Int do return pull_request_url.split("/").last.to_i

	# Link to the pull request on API.
	var pull_request_url: String is writable

	# Diff hunk.
	var diff_hunk: String is writable

	# Path of commented file.
	var path: String is writable

	# Position of the comment on the file.
	var position: nullable Int is writable

	# Original position in the diff.
	var original_position: Int is writable

	# Commit referenced by this comment.
	var commit_id: String is writable

	# Original commit id.
	var original_commit_id: String is writable
end

# An event that occurs on a Github `Issue`.
#
# Should be accessed from `GithubAPI::get_issue_event`.
#
# See <https://developer.github.com/v3/issues/events/>.
class IssueEvent
	serialize

	# Event id on Github.
	var id: Int is writable

	# User that initiated the event.
	var actor: User is writable

	# Creation time as String.
	var created_at: String is writable

	# Event descriptor.
	var event: String is writable

	# Commit linked to this event (if any).
	var commit_id: nullable String is writable

	# Label linked to this event (if any).
	var labl: nullable Label is writable, serialize_as("label")

	# User linked to this event (if any).
	var assignee: nullable User is writable

	# Milestone linked to this event (if any).
	var milestone: nullable Milestone is writable

	# Rename linked to this event (if any).
	var rename: nullable RenameAction is writable
end

# A rename action maintains the name before and after a renaming action.
class RenameAction
	serialize

	# Name before renaming.
	var from: String is writable

	# Name after renaming.
	var to: String is writable
end

#
# Should be accessed from `Repo::contrib_stats`.
#
# See <https://developer.github.com/v3/repos/statistics/>.
class ContributorStats
	super Comparable
	serialize

	redef type OTHER: ContributorStats

	# User these statistics are about.
	var author: User is writable

	# Total number of commit.
	var total: Int is writable

	# Array of weeks of activity with detailed statistics.
	var weeks: Array[ContributorWeek] is writable

	# ContributorStats can be compared on the total amount of commits.
	redef fun <(o) do return total < o.total
end

# Contributor stats weekly hash
class ContributorWeek
	serialize

	# Start of week given a Unix timestamp
	var w: Int

	# Number of additions
	var a: Int

	# Number of deletions
	var d: Int

	# Number of commits
	var c: Int
end

# A Github file representation.
#
# Mostly a wrapper around a json object.
class GithubFile
	serialize

	# File name.
	var filename: String is writable
end

# A list of results returned buy `/search`
class SearchResults
	serialize

	# Total count with other pages
	var total_count: Int

	# Does this page contain all the results?
	var incomplete_results: Bool

	# Results in this page
	var items: Array[Object]
end

# JsonDeserializer specific for Github objects.
class GithubDeserializer
	super JsonDeserializer

	private var pattern_base = "https://api.github.com"

	# Url patterns to class names
	var url_patterns: Map[Regex, String] is lazy do
		var map = new HashMap[Regex, String]
		map["{pattern_base}/users/[^/]*$".to_re] = "User"
		map["{pattern_base}/repos/[^/]*/[^/]*$".to_re] = "Repo"
		map["{pattern_base}/repos/[^/]*/[^/]*/labels/[^/]+$".to_re] = "Label"
		map["{pattern_base}/repos/[^/]*/[^/]*/milestones/[0-9]+$".to_re] = "Milestone"
		map["{pattern_base}/repos/[^/]*/[^/]*/issues/[0-9]+$".to_re] = "Issue"
		map["{pattern_base}/repos/[^/]*/[^/]*/issues/comments/[0-9]+$".to_re] = "IssueComment"
		map["{pattern_base}/repos/[^/]*/[^/]*/issues/events/[0-9]+$".to_re] = "IssueEvent"
		map["{pattern_base}/repos/[^/]*/[^/]*/pulls/[0-9]+$".to_re] = "PullRequest"
		map["{pattern_base}/repos/[^/]*/[^/]*/pulls/comments/[0-9]+$".to_re] = "PullComment"
		map["{pattern_base}/repos/[^/]*/[^/]*/comments/[0-9]+$".to_re] = "CommitComment"
		map["{pattern_base}/repos/[^/]*/[^/]*/commits/[a-f0-9]+$".to_re] = "Commit"
		map["{pattern_base}/repos/[^/]*/[^/]*/commits/[a-f0-9]+/status$".to_re] = "CommitStatus"
		map["{pattern_base}/repos/[^/]*/[^/]*/statuses/[a-f0-9]+$".to_re] = "RepoStatus"
		return map
	end

	# Match `url` property in object to a class name
	fun url_heuristic(raw: Map[String, nullable Object]): nullable String do
		if not raw.has_key("url") then return null

		var url = raw["url"].as(String)
		for re, class_name in url_patterns do
			if url.has(re) then return class_name
		end
		return null
	end

	redef fun class_name_heuristic(raw) do
		# Try with url
		var class_name = url_heuristic(raw)
		if class_name != null then return class_name

		# print raw.serialize_to_json(true, true) # debug

		# Use properties heuristics
		if raw.has_key("name") and raw.has_key("commit") then
			return "Branch"
		else if raw.has_key("total_count") and raw.has_key("items") then
			return "SearchResults"
		else if raw.has_key("total") and raw.has_key("weeks") then
			return "ContributorStats"
		else if raw.has_key("a") and raw.has_key("d") and raw.has_key("c") then
			return "ContributorWeek"
		end
		return null
	end

	redef fun deserialize_class(name) do
		if name == "Issue" then
			var issue = super.as(Issue)
			if path.last.has_key("pull_request") then
				issue.is_pull_request = true
			end
			return issue
		else if name == "Commit" then
			var commit = super.as(Commit)
			var git_commit = commit.commit
			if git_commit != null then commit.message = git_commit.message
			return commit
		end
		return super
	end
end

# Gets the Github token from `git` configuration
#
# Return the value of `git config --get github.oauthtoken`
# or `""` if no key exists.
fun get_github_oauth: String
do
	var p = new ProcessReader("git", "config", "--get", "github.oauthtoken")
	var token = p.read_line
	p.wait
	p.close
	return token.trim
end