docs: basic readme

Author: s-ayush2903

readme.md

@@ -1,6 +1,54 @@
-this is a ~~sample~~ readme, **can** you see it _really_?
-helloooo
-heyyDidOpenTextDocumentParams
+# custom-lsp
+A custom LSP server written in 100% Go. It's purpose was learning about how LSP
+servers actually work at a deeper level, gaining understanding and implementing
+a minimal version of it.
 
-VS C*de is an excellent editor
-VS Code neovim Neovim
+Built with go version 1.22.1 on darwin/arm64, and tested on NEOVIM `v0.9.5`
+(Release) - [link](https://github.com/neovim/neovim/releases/tag/v0.9.5). Should
+work with other editors as well given proper config of lsp at the client end.
+A sample config used for testing this LSP server is linked [here](https://github.com/ayush-oyorooms/.dotfiles/blob/5a7ab2ba1c965cc1bc91de9a646a8a82d68976d1/nvim/.config/nvim/after/plugin/custom_lsp_server_test.lua)
+
+A huuuge thanks to @tjdevries for sparking the interest in LSPs : )
+
+## Functionalities Supported
+### 1. Hover
+This functionality in general displays the function / method / class synopsis as
+a popup in usual editors. It is invoked when cursor is kept on a word for a
+while. Here I have implemented a simple version of it which handles state and
+dynamically tells the char count.
+
+* LSP Spec: [Hover](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_hover)
+* Invocation: `:lua vim.lsp.buf.hover()`
+
+### 2. Go To Definition
+This takes to the definition of the function / method(it is different from
+implementation). This is invoked usually in editors when you 
+`Ctrl / Cmd + click` on a keyword. In this implementaion it takes you to a line
+above where the cursor is at the moment.
+
+* LSP Spec: [Go To Definition](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_definition)
+* Invocation: `:lua vim.lsp.buf.definition()`
+
+### 3. Code Actions
+When there are errors in your project and editor shows options to fix them,
+these are the code actions. The server returns with the possible potential
+solutions to the problems in the current context. This implementation takes it 
+quite seriously xD.
+
+* LSP Spec: [Code Actions](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_codeAction)
+* Invocation: `:lua vim.lsp.buf.code_action()` _or_ `:Telescope diagnostics`
+
+### 4. Completions
+These are simply the suggestions which appear as you type. This implementation
+provides a couple of suggestions based on typing.
+
+* LSP Spec: [Completion](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_completion)
+* Invocation: `:lua vim.lsp.buf.completion()`
+
+### 4. Diagnostics (Notification)
+These are simply the errors, warnings, hints along with some more info related
+to them that editor keeps generating async-ly and shows them in the top right
+section (usually). This implementation takes a few funny takes on editors.
+
+* LSP Spec: [Diagnostics](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_publishDiagnostics)
+* Invocation: `:lua vim.lsp.diagnostic.get_line_diagnostics()`  (these btw get generated in insert mode only)