package diary_test

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log/slog"
	"regexp"
	"strconv"
	"strings"
	"testing"
	"testing/slogtest"

	"git.golem15.com/golem15/summercms/modules/diary"
	"github.com/charmbracelet/colorprofile"
)

// TestSlogtestConsoleHandler: the styled console handler (with the NoTTY
// profile, so its lines carry no escape codes) passes testing/slogtest.
func TestSlogtestConsoleHandler(t *testing.T) {
	var buf bytes.Buffer
	h := diary.NewConsoleHandler(&buf, diary.ConsoleOptions{Profile: colorprofile.NoTTY})
	results := func() []map[string]any {
		var out []map[string]any
		for _, line := range strings.Split(strings.TrimSuffix(buf.String(), "\n"), "\n") {
			if line == "" {
				continue
			}
			m, err := parseConsoleLine(line)
			if err != nil {
				t.Fatalf("unparsable console line %q: %v", line, err)
			}
			out = append(out, m)
		}
		return out
	}
	if err := slogtest.TestHandler(h, results); err != nil {
		t.Fatal(err)
	}
}

// TestSlogtestPipeline: the full pipeline (component handler, sunscreen and
// a stack of a JSON stderr channel and a null channel) passes
// testing/slogtest through its JSON output, for a component logger and for
// the process default.
func TestSlogtestPipeline(t *testing.T) {
	for _, name := range []string{"pipeline", ""} {
		t.Run(fmt.Sprintf("component %q", name), func(t *testing.T) {
			var buf lockedBuffer
			setup(t, diary.Options{Stderr: &buf},
				"SUMMER_LOG__DEFAULT=stack",
				"SUMMER_LOG__CHANNELS__STACK__CHANNELS=stderr,null",
				"SUMMER_LOG__CHANNELS__STDERR__FORMAT=json",
			)
			h := diary.For(name).Handler()
			if name == "" {
				h = slog.Default().Handler()
			}
			results := func() []map[string]any {
				var out []map[string]any
				for _, line := range strings.Split(strings.TrimSpace(buf.String()), "\n") {
					var m map[string]any
					if err := json.Unmarshal([]byte(line), &m); err != nil {
						t.Fatalf("pipeline line is not JSON: %q: %v", line, err)
					}
					if name != "" && m[diary.ComponentKey] != name {
						t.Fatalf("pipeline record lacks component %q: %v", name, m)
					}
					out = append(out, m)
				}
				return out
			}
			if err := slogtest.TestHandler(h, results); err != nil {
				t.Fatal(err)
			}
		})
	}
}

var consoleTime = regexp.MustCompile(`^\d{2}:\d{2}:\d{2} `)

// parseConsoleLine reads one console line without a component: an optional
// HH:MM:SS time, the level, the message (the words before the first
// key=value field) and key=value fields whose dotted keys become nested
// maps. Quoted values are unquoted.
func parseConsoleLine(line string) (map[string]any, error) {
	m := map[string]any{}
	if loc := consoleTime.FindStringIndex(line); loc != nil {
		m[slog.TimeKey] = strings.TrimSpace(line[:loc[1]])
		line = line[loc[1]:]
	}
	level, rest, ok := strings.Cut(line, " ")
	if !ok {
		return nil, fmt.Errorf("no level")
	}
	m[slog.LevelKey] = level
	tokens, err := splitFields(strings.TrimLeft(rest, " "))
	if err != nil {
		return nil, err
	}
	var msg []string
	i := 0
	for ; i < len(tokens) && !strings.Contains(tokens[i], "="); i++ {
		msg = append(msg, tokens[i])
	}
	m[slog.MessageKey] = strings.Join(msg, " ")
	for ; i < len(tokens); i++ {
		key, raw, _ := strings.Cut(tokens[i], "=")
		value := raw
		if strings.HasPrefix(raw, `"`) {
			if value, err = strconv.Unquote(raw); err != nil {
				return nil, fmt.Errorf("value of %s: %w", key, err)
			}
		}
		parts := strings.Split(key, ".")
		cur := m
		for _, p := range parts[:len(parts)-1] {
			next, ok := cur[p].(map[string]any)
			if !ok {
				next = map[string]any{}
				cur[p] = next
			}
			cur = next
		}
		cur[parts[len(parts)-1]] = value
	}
	return m, nil
}

// splitFields splits s on spaces, keeping a double-quoted value (with
// backslash escapes) inside its field.
func splitFields(s string) ([]string, error) {
	var out []string
	for s != "" {
		var b strings.Builder
		for s != "" && s[0] != ' ' {
			if s[0] == '"' {
				end := 1
				for end < len(s) && s[end] != '"' {
					if s[end] == '\\' {
						end++
					}
					end++
				}
				if end >= len(s) {
					return nil, fmt.Errorf("unterminated quote")
				}
				b.WriteString(s[:end+1])
				s = s[end+1:]
				continue
			}
			b.WriteByte(s[0])
			s = s[1:]
		}
		out = append(out, b.String())
		s = strings.TrimLeft(s, " ")
	}
	return out, nil
}