package config

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func write(t *testing.T, body string) string {
	t.Helper()
	path := filepath.Join(t.TempDir(), "config")
	if err := os.WriteFile(path, []byte(body), 0o644); err != nil {
		t.Fatal(err)
	}
	return path
}

func TestLoadMissingFileKeepsDefaults(t *testing.T) {
	cfg, err := Load(filepath.Join(t.TempDir(), "absent"))
	if err != nil {
		t.Fatalf("missing file should not be an error: %v", err)
	}
	if cfg.Hours != 12 || cfg.Icons != "nerd" {
		t.Fatalf("defaults not returned: %+v", cfg)
	}
}

func TestLoadOverridesOnlyWhatIsSet(t *testing.T) {
	cfg, err := Load(write(t, "hours=24\nicons=emoji\n"))
	if err != nil {
		t.Fatal(err)
	}
	if cfg.Hours != 24 {
		t.Errorf("hours = %d, want 24", cfg.Hours)
	}
	if cfg.Icons != "emoji" {
		t.Errorf("icons = %q, want emoji", cfg.Icons)
	}
	// Untouched keys must keep their defaults.
	if cfg.GraphHeight != 5 || !cfg.Graph {
		t.Errorf("unset keys lost their defaults: %+v", cfg)
	}
}

func TestLoadCommentsAndBlanks(t *testing.T) {
	cfg, err := Load(write(t, "\n# a comment\n\nhours=6   # trailing comment\n"))
	if err != nil {
		t.Fatal(err)
	}
	if cfg.Hours != 6 {
		t.Fatalf("hours = %d, want 6 (trailing comment must be stripped)", cfg.Hours)
	}
}

func TestLoadErrors(t *testing.T) {
	for name, body := range map[string]string{
		"no equals":    "hours 12\n",
		"unknown key":  "colour=always\n",
		"not a number": "hours=soon\n",
		"not a bool":   "graph=maybe\n",
	} {
		t.Run(name, func(t *testing.T) {
			if _, err := Load(write(t, body)); err == nil {
				t.Fatalf("expected an error for %q", body)
			}
		})
	}
}

func TestPollenAllAndNone(t *testing.T) {
	cfg, _ := Load(write(t, "pollen=all\n"))
	if len(cfg.Pollen) != len(AllSpecies) {
		t.Errorf("pollen=all gave %v", cfg.Pollen)
	}
	cfg, _ = Load(write(t, "pollen=none\n"))
	if len(cfg.Pollen) != 0 {
		t.Errorf("pollen=none gave %v", cfg.Pollen)
	}
}

func TestValidateNamesTheOffender(t *testing.T) {
	cfg := Default()
	cfg.Columns = []string{"hour", "tempature"}
	err := cfg.Validate()
	if err == nil {
		t.Fatal("expected an error for an unknown column")
	}
	if !strings.Contains(err.Error(), "tempature") {
		t.Errorf("error must name the offending column, got: %v", err)
	}
	if !strings.Contains(err.Error(), "conditions") {
		t.Errorf("error must list valid columns, got: %v", err)
	}
}

func TestValidateRejectsBadEnums(t *testing.T) {
	for name, mutate := range map[string]func(*Config){
		"icons":        func(c *Config) { c.Icons = "pictures" },
		"color":        func(c *Config) { c.Color = "sometimes" },
		"units":        func(c *Config) { c.Units = "furlongs" },
		"hours":        func(c *Config) { c.Hours = 0 },
		"graph_height": func(c *Config) { c.GraphHeight = 1 },
		"pollen":       func(c *Config) { c.Pollen = []string{"oak"} },
	} {
		t.Run(name, func(t *testing.T) {
			cfg := Default()
			mutate(&cfg)
			if err := cfg.Validate(); err == nil {
				t.Fatalf("expected %s to be rejected", name)
			}
		})
	}
}

func TestDefaultIsValid(t *testing.T) {
	if err := Default().Validate(); err != nil {
		t.Fatalf("the built-in default must be valid: %v", err)
	}
}

func TestFieldsRequestsOnlySelectedColumns(t *testing.T) {
	cfg := Default()
	cfg.Columns = []string{"hour", "temp", "wind"}
	got := strings.Join(cfg.Fields(), ",")
	want := "temperature_2m,wind_speed_10m"
	if got != want {
		t.Fatalf("Fields() = %q, want %q", got, want)
	}
}

func TestFieldsDeduplicates(t *testing.T) {
	cfg := Default()
	// icon and conditions both come from weather_code.
	cfg.Columns = []string{"icon", "conditions"}
	if got := cfg.Fields(); len(got) != 1 || got[0] != "weather_code" {
		t.Fatalf("Fields() = %v, want one weather_code", got)
	}
}

func TestWriteDefaultRoundTrips(t *testing.T) {
	path := filepath.Join(t.TempDir(), "sub", "config")
	want := Default()
	want.Location = "Krakow"
	if err := WriteDefault(path, want); err != nil {
		t.Fatal(err)
	}
	got, err := Load(path)
	if err != nil {
		t.Fatalf("the file we generate must parse: %v", err)
	}
	if got.Location != "Krakow" || got.Hours != want.Hours || got.Icons != want.Icons {
		t.Fatalf("round trip changed values:\n got %+v\nwant %+v", got, want)
	}
	if err := got.Validate(); err != nil {
		t.Fatalf("the file we generate must validate: %v", err)
	}
}

func TestCustomColumnDeclaration(t *testing.T) {
	cfg, err := Load(write(t, `columns=hour,temp,birch
column.birch = air:birch_pollen
label.birch = brzoza
width.birch = 7
decimals.birch = 2
suffix.birch = g
`))
	if err != nil {
		t.Fatal(err)
	}
	cc, ok := cfg.Custom["birch"]
	if !ok {
		t.Fatal("birch was not declared")
	}
	if cc.Source != "air" || cc.Field != "birch_pollen" {
		t.Errorf("source/field = %q/%q", cc.Source, cc.Field)
	}
	if cc.Label != "brzoza" || cc.Width != 7 || cc.Decimals != 2 || cc.Suffix != "g" {
		t.Errorf("attributes not parsed: %+v", cc)
	}
	if err := cfg.Validate(); err != nil {
		t.Fatalf("a complete declaration must validate: %v", err)
	}
}

// Only the fields a selected column needs, split by which API serves them.
func TestCustomColumnsSplitFieldsByApi(t *testing.T) {
	cfg, err := Load(write(t, `columns=hour,temp,birch,soil
column.birch = air:birch_pollen
column.soil = forecast:soil_temperature_0cm
`))
	if err != nil {
		t.Fatal(err)
	}
	fc := strings.Join(cfg.Fields(), ",")
	if !strings.Contains(fc, "soil_temperature_0cm") || !strings.Contains(fc, "temperature_2m") {
		t.Errorf("forecast fields = %q", fc)
	}
	if strings.Contains(fc, "birch_pollen") {
		t.Errorf("an air field must not be asked of the forecast API: %q", fc)
	}
	if air := strings.Join(cfg.AirFields(), ","); air != "birch_pollen" {
		t.Errorf("air fields = %q, want birch_pollen", air)
	}
}

// No custom air column means no second request at all.
func TestNoAirFieldsWhenNoneDeclared(t *testing.T) {
	if got := Default().AirFields(); len(got) != 0 {
		t.Fatalf("AirFields() = %v, want empty", got)
	}
}

func TestCustomColumnErrors(t *testing.T) {
	for name, body := range map[string]string{
		"no source":      "column.x = birch_pollen\ncolumns=hour,x\n",
		"unknown source": "column.x = weather:birch_pollen\ncolumns=hour,x\n",
		"empty field":    "column.x = air:\ncolumns=hour,x\n",
		"bad width":      "column.x = air:f\nwidth.x = wide\n",
		"bad decimals":   "column.x = air:f\ndecimals.x = 9\n",
	} {
		t.Run(name, func(t *testing.T) {
			if _, err := Load(write(t, body)); err == nil {
				t.Fatalf("expected an error for %q", body)
			}
		})
	}
}

// Attributes without a declaration are a typo, not a silent no-op.
func TestAttributesWithoutDeclarationAreRejected(t *testing.T) {
	cfg, err := Load(write(t, "label.birch = brzoza\n"))
	if err != nil {
		t.Fatal(err)
	}
	if err := cfg.Validate(); err == nil {
		t.Fatal("label.birch without column.birch must be an error")
	}
}

// Shadowing a built-in would make which column you get depend on lookup order.
func TestCustomColumnCannotShadowABuiltIn(t *testing.T) {
	cfg, err := Load(write(t, "column.temp = air:birch_pollen\n"))
	if err != nil {
		t.Fatal(err)
	}
	err = cfg.Validate()
	if err == nil || !strings.Contains(err.Error(), "built-in") {
		t.Fatalf("expected a built-in clash error, got %v", err)
	}
}

// An undeclared column name should say how to declare it.
func TestUnknownColumnSuggestsDeclaringIt(t *testing.T) {
	cfg := Default()
	cfg.Columns = []string{"hour", "birch"}
	err := cfg.Validate()
	if err == nil || !strings.Contains(err.Error(), "column.birch") {
		t.Fatalf("error should show how to declare it, got %v", err)
	}
}

func TestPollenExplicitTracksWhoChose(t *testing.T) {
	cases := map[string]bool{
		"pollen=grass,birch\n": true,
		"pollen=all\n":         false,
		"pollen=none\n":        false,
	}
	for body, want := range cases {
		cfg, err := Load(write(t, body))
		if err != nil {
			t.Fatal(err)
		}
		if cfg.PollenExplicit != want {
			t.Errorf("%q gave PollenExplicit=%v, want %v", body, cfg.PollenExplicit, want)
		}
	}
	if Default().PollenExplicit {
		t.Error("the default is not an explicit choice")
	}
}