Indent logs with a context manager

Introduces new context manager `LogContext.intentation()`. Usage:

```python
from piptools.loggin import log

log.debug("Hello")

with log.indentation():
  log.debug("World!")
```

Output:

```
Hello
  World!
```

piptools/logging.py

@@ -1,6 +1,7 @@
 # coding: utf-8
 from __future__ import absolute_import, division, print_function, unicode_literals
 
+import contextlib
 import logging
 
 from . import click
@@ -11,12 +12,15 @@
 
 
 class LogContext(object):
-    def __init__(self, verbosity=0):
+    def __init__(self, verbosity=0, indent_width=2):
         self.verbosity = verbosity
+        self.current_indent = 0
+        self._indent_width = indent_width
 
-    def log(self, *args, **kwargs):
+    def log(self, message, *args, **kwargs):
         kwargs.setdefault("err", True)
-        click.secho(*args, **kwargs)
+        prefix = " " * self.current_indent
+        click.secho(prefix + message, *args, **kwargs)
 
     def debug(self, *args, **kwargs):
         if self.verbosity >= 1:
@@ -34,5 +38,22 @@ def error(self, *args, **kwargs):
         kwargs.setdefault("fg", "red")
         self.log(*args, **kwargs)
 
+    def _indent(self):
+        self.current_indent += self._indent_width
+
+    def _dedent(self):
+        self.current_indent -= self._indent_width
+
+    @contextlib.contextmanager
+    def indentation(self):
+        """
+        Increase indentation.
+        """
+        self._indent()
+        try:
+            yield
+        finally:
+            self._dedent()
+
 
 log = LogContext()

piptools/repositories/pypi.py

@@ -267,14 +267,15 @@ def get_hashes(self, ireq):
         )
         matching_candidates = candidates_by_version[matching_versions[0]]
 
-        log.debug("  {}".format(ireq.name))
+        log.debug(ireq.name)
 
-        return {
-            self._get_file_hash(candidate.link) for candidate in matching_candidates
-        }
+        with log.indentation():
+            return {
+                self._get_file_hash(candidate.link) for candidate in matching_candidates
+            }
 
     def _get_file_hash(self, link):
-        log.debug("    Hashing {}".format(link.url_without_fragment))
+        log.debug("Hashing {}".format(link.url_without_fragment))
         h = hashlib.new(FAVORITE_HASH)
         with open_local_or_remote_file(link, self.session) as f:
             # Chunks to iterate
@@ -283,7 +284,12 @@ def _get_file_hash(self, link):
             # Choose a context manager depending on verbosity
             if log.verbosity >= 1:
                 iter_length = f.size / FILE_CHUNK_SIZE if f.size else None
-                context_manager = progressbar(chunks, length=iter_length, label="  ")
+                bar_template = "{prefix}[%(bar)s]  %(info)s".format(
+                    prefix=" " * log.current_indent
+                )
+                context_manager = progressbar(
+                    chunks, length=iter_length, bar_template=bar_template
+                )
             else:
                 context_manager = contextlib.nullcontext(chunks)
 

piptools/resolver.py

@@ -131,7 +131,7 @@ def resolve_hashes(self, ireqs):
         """
         log.debug("")
         log.debug("Generating hashes:")
-        with self.repository.allow_all_wheels():
+        with self.repository.allow_all_wheels(), log.indentation():
             return {ireq: self.repository.get_hashes(ireq) for ireq in ireqs}
 
     def resolve(self, max_rounds=10):
@@ -238,20 +238,23 @@ def _resolve_one_round(self):
         constraints = sorted(self.constraints, key=key_from_ireq)
 
         log.debug("Current constraints:")
-        for constraint in constraints:
-            log.debug("  {}".format(constraint))
+        with log.indentation():
+            for constraint in constraints:
+                log.debug(str(constraint))
 
         log.debug("")
         log.debug("Finding the best candidates:")
-        best_matches = {self.get_best_match(ireq) for ireq in constraints}
+        with log.indentation():
+            best_matches = {self.get_best_match(ireq) for ireq in constraints}
 
         # Find the new set of secondary dependencies
         log.debug("")
         log.debug("Finding secondary dependencies:")
 
         their_constraints = []
-        for best_match in best_matches:
-            their_constraints.extend(self._iter_dependencies(best_match))
+        with log.indentation():
+            for best_match in best_matches:
+                their_constraints.extend(self._iter_dependencies(best_match))
         # Grouping constraints to make clean diff between rounds
         theirs = set(self._group_constraints(sorted(their_constraints, key=str)))
 
@@ -268,11 +271,13 @@ def _resolve_one_round(self):
         if has_changed:
             log.debug("")
             log.debug("New dependencies found in this round:")
-            for new_dependency in sorted(diff, key=key_from_ireq):
-                log.debug("  adding {}".format(new_dependency))
+            with log.indentation():
+                for new_dependency in sorted(diff, key=key_from_ireq):
+                    log.debug("adding {}".format(new_dependency))
             log.debug("Removed dependencies in this round:")
-            for removed_dependency in sorted(removed, key=key_from_ireq):
-                log.debug("  removing {}".format(removed_dependency))
+            with log.indentation():
+                for removed_dependency in sorted(removed, key=key_from_ireq):
+                    log.debug("removing {}".format(removed_dependency))
 
         # Store the last round's results in the their_constraints
         self.their_constraints = theirs
@@ -308,7 +313,7 @@ def get_best_match(self, ireq):
 
         # Format the best match
         log.debug(
-            "  found candidate {} (constraint was {})".format(
+            "found candidate {} (constraint was {})".format(
                 format_requirement(best_match), format_specifier(ireq)
             )
         )
@@ -352,9 +357,7 @@ def _iter_dependencies(self, ireq):
         # from there
         if ireq not in self.dependency_cache:
             log.debug(
-                "  {} not in cache, need to check index".format(
-                    format_requirement(ireq)
-                ),
+                "{} not in cache, need to check index".format(format_requirement(ireq)),
                 fg="yellow",
             )
             dependencies = self.repository.get_dependencies(ireq)
@@ -363,7 +366,7 @@ def _iter_dependencies(self, ireq):
         # Example: ['Werkzeug>=0.9', 'Jinja2>=2.4']
         dependency_strings = self.dependency_cache[ireq]
         log.debug(
-            "  {:25} requires {}".format(
+            "{:25} requires {}".format(
                 format_requirement(ireq),
                 ", ".join(sorted(dependency_strings, key=lambda s: s.lower())) or "-",
             )

piptools/scripts/compile.py

@@ -369,14 +369,16 @@ def cli(
     ]
 
     log.debug("Using indexes:")
-    for index_url in dedup(repository.finder.index_urls):
-        log.debug("  {}".format(index_url))
+    with log.indentation():
+        for index_url in dedup(repository.finder.index_urls):
+            log.debug(index_url)
 
     if repository.finder.find_links:
         log.debug("")
         log.debug("Configuration:")
-        for find_link in dedup(repository.finder.find_links):
-            log.debug("  -f {}".format(find_link))
+        with log.indentation():
+            for find_link in dedup(repository.finder.find_links):
+                log.debug("-f {}".format(find_link))
 
     try:
         resolver = Resolver(

tests/test_logging.py

@@ -0,0 +1,25 @@
+from piptools.logging import LogContext
+
+
+def test_indentation(runner):
+    """
+    Test LogContext.indentation() context manager increases indentation.
+    """
+    log = LogContext(indent_width=2)
+
+    with runner.isolation() as (_, stderr):
+        log.log("Test message 1")
+        with log.indentation():
+            log.log("Test message 2")
+            with log.indentation():
+                log.log("Test message 3")
+            log.log("Test message 4")
+        log.log("Test message 5")
+
+    assert stderr.getvalue().decode().splitlines() == [
+        "Test message 1",
+        "  Test message 2",
+        "    Test message 3",
+        "  Test message 4",
+        "Test message 5",
+    ]