F1 shows man page for current query

pgcli/key_bindings.py

@@ -1,4 +1,6 @@
 import logging
+import click
+import re
 from prompt_toolkit.enums import EditingMode
 from prompt_toolkit.key_binding import KeyBindings
 from prompt_toolkit.filters import (
@@ -8,6 +10,7 @@
     has_selection,
     vi_mode,
 )
+from .man import man
 
 from .pgbuffer import buffer_should_be_handled, safe_multi_line_mode
 
@@ -20,6 +23,20 @@ def pgcli_bindings(pgcli):
 
     tab_insert_text = " " * 4
 
+    @kb.add("f1")
+    def _(event):
+        """Show man page for current command."""
+        _logger.debug("Detected <F1> key.")
+
+        m = re.match(r"^[\w\s]+", event.app.current_buffer.text)
+        if not m:
+            return
+        click.clear()
+        text = m.group()
+        _logger.debug(f"Launching man page for {text}")
+        if not man(text):
+            _logger.debug("Failed to show man page")
+
     @kb.add("f2")
     def _(event):
         """Enable/Disable SmartCompletion Mode."""

pgcli/man.py

@@ -0,0 +1,44 @@
+import subprocess
+
+IGNORED = [
+    "OR",
+    "REPLACE",
+    "DEFAULT",
+    "UNIQUE",
+    "TRUSTED",
+    "PROCEDURAL",
+    "TEMP",
+    "TEMPORARY",
+    "UNLOGGED",
+    "GLOBAL",
+    "LOCAL",
+    "CONSTRAINT",
+    "RECURSIVE",
+    "WORK",
+    "TRANSACTION",
+    "SESSION",
+]
+
+
+def try_man(page):
+    try:
+        subprocess.run(
+            f"man -I 7 {page}", shell=True, check=True, universal_newlines=True
+        )
+        return True
+    except subprocess.CalledProcessError:
+        return False
+
+
+def man(query):
+    words = query.strip().split()[:6]
+    words = map(lambda e: e.upper(), words)
+    words = list(filter(lambda e: e not in IGNORED, words))
+    if not words:
+        return True
+    if words[0] == "RELEASE":
+        words.insert(1, "SAVEPOINT")
+    for i in [2, 1, 3, 4]:
+        if try_man("_".join(words[0 : i + 1])):
+            return True
+    return False