# coding: utf-8
require "octokit"
require "danger/helpers/comments_helper"
require "danger/helpers/comment"
require "danger/request_sources/github/github_review"
require "danger/request_sources/github/github_review_unsupported"
require "danger/request_sources/github/octokit_pr_review"
require "danger/request_sources/support/get_ignored_violation"

module Danger
  module RequestSources
    class GitHub < RequestSource
      include Danger::Helpers::CommentsHelper

      attr_accessor :pr_json, :issue_json, :support_tokenless_auth

      def self.env_vars
        ["DANGER_GITHUB_API_TOKEN"]
      end

      def self.optional_env_vars
        ["DANGER_GITHUB_HOST", "DANGER_GITHUB_API_BASE_URL"]
      end

      def initialize(ci_source, environment)
        self.ci_source = ci_source
        self.environment = environment
        self.support_tokenless_auth = false

        @token = @environment["DANGER_GITHUB_API_TOKEN"]
      end

      def validates_as_api_source?
        (@token && !@token.empty?) || self.environment["DANGER_USE_LOCAL_GIT"]
      end

      def scm
        @scm ||= GitRepo.new
      end

      def host
        @host = @environment["DANGER_GITHUB_HOST"] || "github.com"
      end

      # `DANGER_GITHUB_API_HOST` is the old name kept for legacy reasons and
      # backwards compatibility. `DANGER_GITHUB_API_BASE_URL` is the new
      # correctly named variable.
      def api_url
        @environment.fetch("DANGER_GITHUB_API_HOST") do
          @environment.fetch("DANGER_GITHUB_API_BASE_URL") do
            "https://api.github.com/".freeze
          end
        end
      end

      def client
        raise "No API token given, please provide one using `DANGER_GITHUB_API_TOKEN`" if !@token && !support_tokenless_auth

        @client ||= begin
          Octokit::Client.new(access_token: @token, auto_paginate: true, api_endpoint: api_url)
        end
      end

      def pr_diff
        @pr_diff ||= client.pull_request(ci_source.repo_slug, ci_source.pull_request_id, accept: "application/vnd.github.v3.diff")
      end

      def review
        return @review unless @review.nil?
        begin
          @review = client.pull_request_reviews(ci_source.repo_slug, ci_source.pull_request_id)
            .map { |review_json| Danger::RequestSources::GitHubSource::Review.new(client, ci_source, review_json) }
            .select(&:generated_by_danger?)
            .last
          @review ||= Danger::RequestSources::GitHubSource::Review.new(client, ci_source)
          @review
        rescue Octokit::NotFound
          @review = Danger::RequestSources::GitHubSource::ReviewUnsupported.new
          @review
        end
      end

      def setup_danger_branches
        # we can use a github specific feature here:
        base_commit = self.pr_json["base"]["sha"]
        head_commit = self.pr_json["head"]["sha"]

        # Next, we want to ensure that we have a version of the current branch at a known location
        scm.ensure_commitish_exists! base_commit
        self.scm.exec "branch #{EnvironmentManager.danger_base_branch} #{base_commit}"

        # OK, so we want to ensure that we have a known head branch, this will always represent
        # the head of the PR ( e.g. the most recent commit that will be merged. )
        scm.ensure_commitish_exists! head_commit
        self.scm.exec "branch #{EnvironmentManager.danger_head_branch} #{head_commit}"
      end

      def fetch_details
        self.pr_json = client.pull_request(ci_source.repo_slug, ci_source.pull_request_id)
        if self.pr_json["message"] == "Moved Permanently"
          raise "Repo moved or renamed, make sure to update the git remote".red
        end

        fetch_issue_details(self.pr_json)
        self.ignored_violations = ignored_violations_from_pr
      end

      def ignored_violations_from_pr
        GetIgnoredViolation.new(self.pr_json["body"]).call
      end

      def fetch_issue_details(pr_json)
        href = pr_json["_links"]["issue"]["href"]
        self.issue_json = client.get(href)
      end

      def issue_comments
        @comments ||= begin
          client.issue_comments(ci_source.repo_slug, ci_source.pull_request_id)
            .map { |comment| Comment.from_github(comment) }
        end
      end

      # Sending data to GitHub
      def update_pull_request!(warnings: [], errors: [], messages: [], markdowns: [], danger_id: "danger", new_comment: false)
        comment_result = {}
        editable_comments = issue_comments.select { |comment| comment.generated_by_danger?(danger_id) }
        last_comment = editable_comments.last
        should_create_new_comment = new_comment || last_comment.nil?

        if should_create_new_comment
          previous_violations = {}
        else
          previous_violations = parse_comment(last_comment.body)
        end

        main_violations = (warnings + errors + messages + markdowns).reject(&:inline?)
        if previous_violations.empty? && main_violations.empty?
          # Just remove the comment, if there's nothing to say.
          delete_old_comments!(danger_id: danger_id)
        end

        cmp = proc do |a, b|
          next -1 unless a.file
          next 1 unless b.file

          next a.line <=> b.line if a.file == b.file
          next a.file <=> b.file
        end

        # Sort to group inline comments by file
        # We copy because we need to mutate this arrays for inlines
        comment_warnings = warnings.sort(&cmp)
        comment_errors = errors.sort(&cmp)
        comment_messages = messages.sort(&cmp)
        comment_markdowns = markdowns.sort(&cmp)

        submit_inline_comments!(warnings: comment_warnings,
                                  errors: comment_errors,
                                messages: comment_messages,
                                markdowns: comment_markdowns,
                      previous_violations: previous_violations,
                                danger_id: danger_id)

        # If there are still violations to show
        unless main_violations.empty?
          body = generate_comment(warnings: comment_warnings,
                                    errors: comment_errors,
                                  messages: comment_messages,
                                  markdowns: comment_markdowns,
                        previous_violations: previous_violations,
                                  danger_id: danger_id,
                                  template: "github")

          if should_create_new_comment
            comment_result = client.add_comment(ci_source.repo_slug, ci_source.pull_request_id, body)
          else
            comment_result = client.update_comment(ci_source.repo_slug, last_comment.id, body)
          end
        end

        # Now, set the pull request status.
        # Note: this can terminate the entire process.
        submit_pull_request_status!(warnings: warnings,
                                      errors: errors,
                                 details_url: comment_result["html_url"],
                                   danger_id: danger_id)
      end

      def submit_pull_request_status!(warnings: [], errors: [], details_url: [], danger_id: "danger")
        status = (errors.count.zero? ? "success" : "failure")
        message = generate_description(warnings: warnings, errors: errors)
        latest_pr_commit_ref = self.pr_json["head"]["sha"]

        if latest_pr_commit_ref.empty? || latest_pr_commit_ref.nil?
          raise "Couldn't find a commit to update its status".red
        end

        begin
          client.create_status(ci_source.repo_slug, latest_pr_commit_ref, status, {
            description: message,
            context: "danger/#{danger_id}",
            target_url: details_url
          })
        rescue
          # This usually means the user has no commit access to this repo
          # That's always the case for open source projects where you can only
          # use a read-only GitHub account
          if errors.count > 0
            # We need to fail the actual build here
            is_private = pr_json["base"]["repo"]["private"]
            if is_private
              abort("\nDanger has failed this build. \nFound #{'error'.danger_pluralize(errors.count)} and I don't have write access to the PR to set a PR status.")
            else
              abort("\nDanger has failed this build. \nFound #{'error'.danger_pluralize(errors.count)}.")
            end
          else
            puts message
            puts "\nDanger does not have write access to the PR to set a PR status.".yellow
          end
        end
      end

      # Get rid of the previously posted comment, to only have the latest one
      def delete_old_comments!(except: nil, danger_id: "danger")
        issue_comments.each do |comment|
          next unless comment.generated_by_danger?(danger_id)
          next if comment.id == except
          client.delete_comment(ci_source.repo_slug, comment.id)
        end
      end

      def submit_inline_comments!(warnings: [], errors: [], messages: [], markdowns: [], previous_violations: [], danger_id: "danger")
        # Avoid doing any fetchs if there's no inline comments
        return if (warnings + errors + messages).select(&:inline?).empty?

        diff_lines = self.pr_diff.lines
        pr_comments = client.pull_request_comments(ci_source.repo_slug, ci_source.pull_request_id)
        danger_comments = pr_comments.select { |comment| Comment.from_github(comment).generated_by_danger?(danger_id) }
        non_danger_comments = pr_comments - danger_comments

        submit_inline_comments_for_kind!("warning", warnings, diff_lines, danger_comments, previous_violations["warning"], danger_id: danger_id)
        submit_inline_comments_for_kind!("no_entry_sign", errors, diff_lines, danger_comments, previous_violations["error"], danger_id: danger_id)
        submit_inline_comments_for_kind!("book", messages, diff_lines, danger_comments, previous_violations["message"], danger_id: danger_id)
        submit_inline_comments_for_kind!(nil, markdowns, diff_lines, danger_comments, [], danger_id: danger_id)

        # submit removes from the array all comments that are still in force
        # so we strike out all remaining ones
        danger_comments.each do |comment|
          violation = violations_from_table(comment["body"]).first
          if !violation.nil? && violation.sticky
            body = generate_inline_comment_body("white_check_mark", violation, danger_id: danger_id, resolved: true, template: "github")
            client.update_pull_request_comment(ci_source.repo_slug, comment["id"], body)
          else
            # We remove non-sticky violations that have no replies
            # Since there's no direct concept of a reply in GH, we simply consider
            # the existance of non-danger comments in that line as replies
            replies = non_danger_comments.select do |potential|
              potential["path"] == comment["path"] &&
                potential["position"] == comment["position"] &&
                potential["commit_id"] == comment["commit_id"]
            end

            client.delete_pull_request_comment(ci_source.repo_slug, comment["id"]) if replies.empty?
          end
        end
      end

      def messages_are_equivalent(m1, m2)
        blob_regexp = %r{blob/[0-9a-z]+/}
        m1.file == m2.file && m1.line == m2.line &&
          m1.message.sub(blob_regexp, "") == m2.message.sub(blob_regexp, "")
      end

      def submit_inline_comments_for_kind!(emoji, messages, diff_lines, danger_comments, previous_violations, danger_id: "danger")
        head_ref = pr_json["head"]["sha"]
        previous_violations ||= []
        is_markdown_content = emoji.nil?

        submit_inline = proc do |m|
          next false unless m.file && m.line

          position = find_position_in_diff diff_lines, m

          # Keep the change if it's line is not in the diff
          next false if position.nil?

          # Once we know we're gonna submit it, we format it
          if is_markdown_content
            body = generate_inline_markdown_body(m, danger_id: danger_id, template: "github")
          else
            # Hide the inline link behind a span
            m = process_markdown(m, true)
            body = generate_inline_comment_body(emoji, m, danger_id: danger_id, template: "github")
            # A comment might be in previous_violations because only now it's part of the unified diff
            # We remove from the array since it won't have a place in the table anymore
            previous_violations.reject! { |v| messages_are_equivalent(v, m) }
          end

          matching_comments = danger_comments.select do |comment_data|
            if comment_data["path"] == m.file && comment_data["commit_id"] == head_ref && comment_data["position"] == position
              # Parse it to avoid problems with strikethrough
              violation = violations_from_table(comment_data["body"]).first
              if violation
                messages_are_equivalent(violation, m)
              else
                comment_data["body"] == body
              end
            else
              false
            end
          end

          if matching_comments.empty?
            client.create_pull_request_comment(ci_source.repo_slug, ci_source.pull_request_id,
                                               body, head_ref, m.file, position)
          else
            # Remove the surviving comment so we don't strike it out
            danger_comments.reject! { |c| matching_comments.include? c }

            # Update the comment to remove the strikethrough if present
            comment = matching_comments.first
            client.update_pull_request_comment(ci_source.repo_slug, comment["id"], body)
          end

          # Remove this element from the array
          next true
        end

        messages.reject!(&submit_inline)
      end

      def find_position_in_diff(diff_lines, message)
        range_header_regexp = /@@ -([0-9]+),([0-9]+) \+(?<start>[0-9]+)(,(?<end>[0-9]+))? @@.*/
        file_header_regexp = %r{ a/.*}

        pattern = "+++ b/" + message.file + "\n"
        file_start = diff_lines.index(pattern)

        return nil if file_start.nil?

        position = -1
        file_line = nil

        diff_lines.drop(file_start).each do |line|
          match = line.match range_header_regexp

          # file_line is set once we find the hunk the line is in
          # we need to count how many lines in new file we have
          # so we do it one by one ignoring the deleted lines
          if !file_line.nil? && !line.start_with?("-")
            break if file_line == message.line
            file_line += 1
          end

          # We need to count how many diff lines are between us and
          # the line we're looking for
          position += 1

          next unless match

          # If we found the start of another file diff, we went too far
          break if line.match file_header_regexp

          range_start = match[:start].to_i
          if match[:end]
            range_end = match[:end].to_i + range_start
          else
            range_end = range_start
          end

          # We are past the line position, just abort
          break if message.line.to_i < range_start
          next unless message.line.to_i >= range_start && message.line.to_i <= range_end

          file_line = range_start
        end

        position unless file_line.nil?
      end

      # See the tests for examples of data coming in looks like
      def parse_message_from_row(row)
        message_regexp = %r{(<(a |span data-)href="https://github.com/#{ci_source.repo_slug}/blob/[0-9a-z]+/(?<file>[^#]+)#L(?<line>[0-9]+)"(>[^<]*</a> - |/>))?(?<message>.*?)}im
        match = message_regexp.match(row)

        if match[:line]
          line = match[:line].to_i
        else
          line = nil
        end
        Violation.new(row, true, match[:file], line)
      end

      def markdown_link_to_message(message, hide_link)
        url = "https://github.com/#{ci_source.repo_slug}/blob/#{pr_json['head']['sha']}/#{message.file}#L#{message.line}"

        if hide_link
          "<span data-href=\"#{url}\"/>"
        else
          "[#{message.file}#L#{message.line}](#{url}) - "
        end
      end

      # @return [String] The organisation name, is nil if it can't be detected
      def organisation
        matched = self.issue_json["repository_url"].match(%r{repos\/(.*)\/})
        return matched[1] if matched && matched[1]
      rescue
        nil
      end

      # @return [String] A URL to the specific file, ready to be downloaded
      def file_url(organisation: nil, repository: nil, branch: "master", path: nil)
        organisation ||= self.organisation
        "https://raw.githubusercontent.com/#{organisation}/#{repository}/#{branch}/#{path}"
      end
    end
  end
end