From c393792cd10a889fb7071944ed9cb9ef0ce3fde9 Mon Sep 17 00:00:00 2001
From: Emil Lerch <emil@lerch.org>
Date: Thu, 25 May 2023 14:18:49 -0700
Subject: [PATCH] add config

---
 src/config.zig | 107 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.zig   |   5 ++-
 2 files changed, 111 insertions(+), 1 deletion(-)
 create mode 100644 src/config.zig

diff --git a/src/config.zig b/src/config.zig
new file mode 100644
index 0000000..eab3bea
--- /dev/null
+++ b/src/config.zig
@@ -0,0 +1,107 @@
+const Self = @This();
+const std = @import("std");
+
+allocator: std.mem.Allocator,
+
+pub const ParsedConfig = struct {
+    key_value_map: *std.StringArrayHashMap([]u8),
+    value_key_map: *std.StringArrayHashMap(*std.ArrayList([]u8)),
+
+    config_allocator: std.mem.Allocator,
+    const SelfConfig = @This();
+
+    var by_keys: std.StringArrayHashMap([]u8) = undefined;
+    var by_values: std.StringArrayHashMap(*std.ArrayList([]u8)) = undefined;
+
+    pub fn init(config_allocator: std.mem.Allocator) SelfConfig {
+        by_keys = std.StringArrayHashMap([]u8).init(config_allocator);
+        by_values = std.StringArrayHashMap(*std.ArrayList([]u8)).init(config_allocator);
+        return SelfConfig{
+            .config_allocator = config_allocator,
+            .key_value_map = &by_keys,
+            .value_key_map = &by_values,
+        };
+    }
+
+    pub fn deinit(self: *SelfConfig) void {
+        for (self.key_value_map.keys(), self.key_value_map.values()) |k, v| {
+            self.config_allocator.free(k); // this is also the key in value_key_map
+            self.config_allocator.free(v);
+        }
+
+        self.key_value_map.deinit();
+        for (self.value_key_map.values()) |v| {
+            // The string in the value array is the same as the one in the key
+            // no need to free
+            // for (v.items) |item| {
+            //     self.config_allocator.free(item);
+            // }
+            v.deinit();
+            self.config_allocator.destroy(v);
+        }
+        // These were already freed above
+        // for (self.value_key_map.keys()) |*k| {
+        //     self.config_allocator.free(k.*);
+        // }
+        self.value_key_map.deinit();
+    }
+};
+
+pub fn init(allocator: std.mem.Allocator) Self {
+    return Self{
+        .allocator = allocator,
+    };
+}
+
+/// Based on a reader, the return will be an ordered list of entries. The
+/// key is a path prefix, while the value is the library to use
+/// caller owns the allocated memory
+pub fn parse(self: Self, reader: anytype) !ParsedConfig {
+    const ws = " \t";
+    var rc = ParsedConfig.init(self.allocator);
+    errdefer rc.deinit();
+    while (try reader.readUntilDelimiterOrEofAlloc(self.allocator, '\n', std.math.maxInt(usize))) |line| {
+        defer self.allocator.free(line);
+        const nocomments = std.mem.trim(u8, @constCast(&std.mem.split(u8, line, "#")).first(), ws);
+        var data_iterator = std.mem.split(u8, nocomments, "=");
+        var key = std.mem.trim(u8, data_iterator.first(), ws); // first never fails
+        if (key.len == 0) continue;
+        var value = std.mem.trim(u8, data_iterator.next() orelse return error.NoValueForKey, ws);
+        // keys should be putNoClobber, but values can be put.
+        // Because we have to dup the memory here though, we want to
+        // manage duplicate values seperately
+        var dup_key = try self.allocator.dupe(u8, key);
+        var dup_value = try self.allocator.dupe(u8, value);
+        try rc.key_value_map.putNoClobber(dup_key, dup_value);
+        if (!rc.value_key_map.contains(value)) {
+            var keys = try self.allocator.create(std.ArrayList([]u8));
+            keys.* = std.ArrayList([]u8).init(self.allocator);
+            try rc.value_key_map.put(dup_value, keys);
+        }
+        try rc.value_key_map.get(value).?.append(dup_key);
+    }
+    return rc;
+}
+
+test "gets config from a stream" {
+    var allocator = std.testing.allocator;
+    var stream = std.io.fixedBufferStream(
+        \\# This is a simple "path prefix" = dynamic library path mapping
+        \\  # no reordering will be done, so you must do things most -> least specific
+        \\   
+        \\
+        \\foo =     bar
+        \\
+        \\baz= qux# what *is* this?
+        \\
+        \\
+        \\bar =foo
+        \\qaz=foo
+    );
+
+    var config = try Self.init(allocator).parse(stream.reader());
+    defer config.deinit();
+    try std.testing.expectEqual(@as(usize, 4), config.key_value_map.keys().len);
+    try std.testing.expectEqual(@as(usize, 3), config.value_key_map.keys().len);
+    try std.testing.expectEqual(@as(usize, 2), config.value_key_map.get("foo").?.items.len);
+}
diff --git a/src/main.zig b/src/main.zig
index 7b55bc8..6f3632e 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -2,10 +2,11 @@ const std = @import("std");
 const builtin = @import("builtin");
 const interface = @import("interface.zig");
 const Watch = @import("Watch.zig");
+const config = @import("config.zig");
+
 const serveFn = *const fn (*interface.Request) ?*interface.Response;
 const zigInitFn = *const fn (*anyopaque) void;
 const requestDeinitFn = *const fn () void;
-
 const timeout = 250;
 
 const FullReturn = struct {
@@ -414,6 +415,8 @@ test {
     // `@This()` is a builtin function that returns the innermost container it is called from.
     // In this example, the innermost container is this file (implicitly a struct).
     std.testing.refAllDecls(@This());
+    std.testing.refAllDecls(config);
+    std.testing.refAllDecls(interface);
 }
 var test_resp_buf: [1024]u8 = undefined;
 var test_resp_buf_len: usize = undefined;