Performance: do not fetch extra post data unless needed

[mo2menelzeiny]

Summary

1. Lazily resolves the scope channel and team only when the scope is defined
2. Adds gating conditions rather than nested if
3. Moves the API call logic to a separate function
4. Increases coverage on ProcessPosts

Ticket Link

Closes #87

[levb]

Thank you for the contribution! One style suggestion.

[iomodo]

Thanks for the contribution @mo2menelzeiny.
Let me understand the overall logic here. We traverse the markdown tree with Inspect which basically calls passed function for every node(let's say N nodes). In the function itself for each link where we have a scope we call the inScope method. Let's assume we have M links, this makes O(N*M) calls of the inScope(and resolveScope respectively).
Return values of team.Name and channel.Name will be the same for every call. Am I missing something? Why not call resolveScope method just once before the Inspect?

[mo2menelzeiny]

Thanks for the contribution @mo2menelzeiny.
Let me understand the overall logic here. We traverse the markdown tree with Inspect which basically calls passed function for every node(let's say N nodes). In the function itself for each link where we have a scope we call the inScope method. Let's assume we have M links, this makes O(N*M) calls of the inScope(and resolveScope respectively).
Return values of team.Name and channel.Name will be the same for every call. Am I missing something? Why not call resolveScope method just once before the Inspect?

@iomodo I don't know how I missed this, you're definitely right.

[iomodo]

Awesome @mo2menelzeiny !
Just two minor improvements below.

[iomodo]

@mo2menelzeiny, Sorry for being pain in the neck, couple more very minor comments below :)

[codecov-io]

Codecov Report

Merging #105 into master will increase coverage by 5.46%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #105      +/-   ##
==========================================
+ Coverage   42.62%   48.09%   +5.46%     
==========================================
  Files           6        6              
  Lines         563      576      +13     
==========================================
+ Hits          240      277      +37     
+ Misses        303      282      -21     
+ Partials       20       17       -3     

Impacted Files	Coverage Δ
server/autolinkplugin/plugin.go	92.00% <100.00%> (+22.35%)	⬆️

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[iomodo]

Thanks a lot @mo2menelzeiny ! Great work!

[mo2menelzeiny]

Hey guys, @DHaussermann @levb @iomodo
are there any troubles with this?

[levb]

@mo2menelzeiny Apologies for the wait, but we are heavily backlogged in QA, and this requires QA verification before it's merged.

[DHaussermann]

Tested and passed

• Regression tested that scope is applied correctly to Teams and combinations of Teams and Channels
• Tested that scope is correctly applied when added and updated
• Tested that scope rules are correctly applied when updating existing post
• Other brief regression testing.
  LGTM!

Sorry for the delay on testing this PR @mo2menelzeiny. Huge thanks for this improvement!

[mo2menelzeiny]

@levb @iomodo @DHaussermann
I think the pull request is now ready for merging, am I right?