package ezconf

import (
	"testing"
)

func TestParseEzconfTag(t *testing.T) {
	tests := []struct {
		name        string
		tag         string
		wantEnvVar  *EnvVar
		expectError bool
	}{
		{
			name: "simple env variable",
			tag:  "LOG_LEVEL,description:Log level for the application",
			wantEnvVar: &EnvVar{
				Name:        "LOG_LEVEL",
				Description: "Log level for the application",
				Required:    false,
				Default:     "",
			},
			expectError: false,
		},
		{
			name: "env variable with default",
			tag:  "LOG_LEVEL,description:Log level for the application,default:info",
			wantEnvVar: &EnvVar{
				Name:        "LOG_LEVEL",
				Description: "Log level for the application",
				Required:    false,
				Default:     "info",
			},
			expectError: false,
		},
		{
			name: "required env variable",
			tag:  "DATABASE_URL,description:Database connection string,required",
			wantEnvVar: &EnvVar{
				Name:        "DATABASE_URL",
				Description: "Database connection string",
				Required:    true,
				Default:     "",
			},
			expectError: false,
		},
		{
			name: "required with condition and default",
			tag:  "LOG_DIR,description:Directory for log files,required:when LOG_OUTPUT is file,default:/var/log",
			wantEnvVar: &EnvVar{
				Name:        "LOG_DIR",
				Description: "Directory for log files (required when LOG_OUTPUT is file)",
				Required:    true,
				Default:     "/var/log",
			},
			expectError: false,
		},
		{
			name: "name only",
			tag:  "SIMPLE_VAR",
			wantEnvVar: &EnvVar{
				Name:        "SIMPLE_VAR",
				Description: "",
				Required:    false,
				Default:     "",
			},
			expectError: false,
		},
		{
			name:        "empty tag",
			tag:         "",
			wantEnvVar:  nil,
			expectError: true,
		},
		{
			name:        "empty name",
			tag:         ",description:some desc",
			wantEnvVar:  nil,
			expectError: true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			envVar, err := parseEzconfTag(tt.tag)

			if tt.expectError {
				if err == nil {
					t.Errorf("expected error but got none")
				}
				return
			}

			if err != nil {
				t.Errorf("unexpected error: %v", err)
				return
			}

			if envVar.Name != tt.wantEnvVar.Name {
				t.Errorf("Name = %v, want %v", envVar.Name, tt.wantEnvVar.Name)
			}
			if envVar.Description != tt.wantEnvVar.Description {
				t.Errorf("Description = %v, want %v", envVar.Description, tt.wantEnvVar.Description)
			}
			if envVar.Required != tt.wantEnvVar.Required {
				t.Errorf("Required = %v, want %v", envVar.Required, tt.wantEnvVar.Required)
			}
			if envVar.Default != tt.wantEnvVar.Default {
				t.Errorf("Default = %v, want %v", envVar.Default, tt.wantEnvVar.Default)
			}
		})
	}
}

func TestParseConfigStruct(t *testing.T) {
	type TestConfig struct {
		LogLevel    string `ezconf:"LOG_LEVEL,description:Log level for the application,default:info"`
		LogOutput   string `ezconf:"LOG_OUTPUT,description:Output destination,default:console"`
		DatabaseURL string `ezconf:"DATABASE_URL,description:Database connection string,required"`
		NoTag       string
	}

	envVars, err := ParseConfigStruct(&TestConfig{})
	if err != nil {
		t.Fatalf("ParseConfigStruct failed: %v", err)
	}

	if len(envVars) != 3 {
		t.Errorf("expected 3 env vars, got %d", len(envVars))
	}

	// Check first variable
	if envVars[0].Name != "LOG_LEVEL" {
		t.Errorf("expected LOG_LEVEL, got %s", envVars[0].Name)
	}
	if envVars[0].Default != "info" {
		t.Errorf("expected default 'info', got %s", envVars[0].Default)
	}

	// Check required variable
	if envVars[2].Name != "DATABASE_URL" {
		t.Errorf("expected DATABASE_URL, got %s", envVars[2].Name)
	}
	if !envVars[2].Required {
		t.Error("expected DATABASE_URL to be required")
	}
}

func TestParseConfigStruct_NilPointer(t *testing.T) {
	_, err := ParseConfigStruct(nil)
	if err == nil {
		t.Error("expected error for nil pointer")
	}
}

func TestParseConfigStruct_NotPointer(t *testing.T) {
	type TestConfig struct {
		Foo string `ezconf:"FOO,description:test"`
	}
	_, err := ParseConfigStruct(TestConfig{})
	if err == nil {
		t.Error("expected error for non-pointer")
	}
}

func TestParseConfigStruct_NotStruct(t *testing.T) {
	str := "not a struct"
	_, err := ParseConfigStruct(&str)
	if err == nil {
		t.Error("expected error for non-struct pointer")
	}
}

func TestParseConfigStruct_NoTags(t *testing.T) {
	type EmptyConfig struct {
		Foo string
		Bar int
	}

	envVars, err := ParseConfigStruct(&EmptyConfig{})
	if err != nil {
		t.Fatalf("ParseConfigStruct failed: %v", err)
	}

	if len(envVars) != 0 {
		t.Errorf("expected 0 env vars for struct with no tags, got %d", len(envVars))
	}
}

func TestParseConfigStruct_UnexportedFields(t *testing.T) {
	type TestConfig struct {
		exported   string `ezconf:"EXPORTED,description:An exported field"`
		unexported string `ezconf:"UNEXPORTED,description:An unexported field"`
	}

	envVars, err := ParseConfigStruct(&TestConfig{})
	if err != nil {
		t.Fatalf("ParseConfigStruct failed: %v", err)
	}

	if len(envVars) != 2 {
		t.Errorf("expected 2 env vars (both exported and unexported), got %d", len(envVars))
	}
}

func TestParseConfigStruct_InvalidTag(t *testing.T) {
	type TestConfig struct {
		Bad string `ezconf:",description:missing name"`
	}

	_, err := ParseConfigStruct(&TestConfig{})
	if err == nil {
		t.Error("expected error for invalid tag")
	}
}