Run second grep relative to first find - bash

Question

I need to find a specific string in a text, and then base on the position of the string, find a second string that is the closes to it (backwards) and print the information. I've got the following:
<tile x="143" y="43" z="7">
<item id="2656"/>
<item id="2111" count="5"/>
<item id="2194"/>
<item id="2205"/>
<item id="2400"/>
</tile>
<tile x="143" y="44" z="7">
<item id="2656"/>
<item id="2111" count="5"/>
<item id="2194"/>
<item id="2205"/>
</tile>
<tile x="143" y="45" z="7">
<item id="2656"/>
<item id="2111" count="5"/>
<item id="2194"/>
<item id="2205"/>
</tile>
<tile x="144" y="43" z="7">
<item id="2656"/>
<item id="2194"/>
<item id="2111" count="5"/>
<item id="2506" special_description="something something something (Arm:12) [Test]"/>
<item id="2194"/>
<item id="2216"/>
<item id="2400"/>
</tile>
<tile x="144" y="44" z="7">
<item id="2656"/>
<item id="2111" count="5"/>
<item id="2194"/>
<item id="2418"/>
<item id="2216"/>
<item id="2431"/>
</tile>
<tile x="144" y="45" z="7">
<item id="2656"/>
<item id="2658"/>
<item id="2111" count="5"/>
<item id="2506" special_description="something something (Arm:12) [Whatever]"/>
<item id="2194"/>
<item id="2216"/>
</tile>
<tile x="146" y="43" z="7">
<item id="1738"/>
<item id="1738"/>
<item id="1738"/>
<item id="2160" count="50"/>
<item id="2183"/>
<item id="2127"/>
<item id="2127"/>
<item id="2205"/>
<item id="2506"/>
<item id="2127"/>
</tile>
The text is all one line, I've split it in separate lines for it to be easier to look through. Originally it looks like this:
<tile x="143" y="43" z="7"><item id="2656"/><item id="2111" count="5"/><item id="2194"/><item id="2205"/><item id="2400"/></tile><tile x="143" y="44" z="7">...
Let's say I'm looking for 2 specific item id's - 2506 and 2418. I've found 2506 in the fourth tile block using grep, now I want to see what tile coordinates it has:
I've found this:
<item id="2506" special_description="something something something (Arm:12) [Test]"/>
and right above it I find this:
<tile x="144" y="43" z="7">
How would I be able to extract the tile information for all those, get the special description if it exists and generate a log?
Ideally it would look like this (but the output is not too important as long as I get all the information extracted):
2506:
144,43,7 | [Test]
144,45,7 | [Whatever]
146,43,7 |
2418:
144,44,7 |
Ideally if someone could get me a ready solution, it'd be much appreciated, but just a helpful pointer would be sufficient!

Answer 1

awk to the rescue!
this may get you started...
$ awk -F'\n' -v RS= '/id="2506"/{print $1}' file
<tile x="144" y="43" z="7">
<tile x="144" y="45" z="7">
<tile x="146" y="43" z="7">

Answer 2

It's better to write a script to do this. Here is the pseudo code:
for all lines in file do {
if line =~ /pattern1/ {
match1 = line
}
elsif line =~ /pattern2/ {
echo line, match1
}
}