package render

import (
	"fmt"
	"strings"

	"github.com/lukaszkasprzak/prognosis/internal/config"
	"github.com/lukaszkasprzak/prognosis/internal/openmeteo"
)

// cell is one rendered table cell: text, its colour, and how it is aligned.
type cell struct {
	text  string
	style string
	left  bool
}

// custom returns the config's definition of a column, if it has one.
func (x ctx) custom(name string) (config.CustomColumn, bool) {
	cc, ok := x.cfg.Custom[name]
	return cc, ok
}

// customLabel is the header for a custom column: what the user asked for, or
// the column's own name.
func customLabel(name string, cc config.CustomColumn) string {
	if cc.Label != "" {
		return cc.Label
	}
	return name
}

// colWidth is the reserved display width per column.
func (x ctx) colWidth(name string) int {
	if cc, ok := x.custom(name); ok {
		if cc.Width > 0 {
			return cc.Width
		}
		// Wide enough for the header, and for a value of a few digits.
		w := DisplayWidth(customLabel(name, cc))
		if w < 5 {
			w = 5
		}
		return w
	}
	switch name {
	case "hour":
		// Three, not two: the Python leaves a double space after the hour.
		return 3
	case "icon":
		return IconWidth(x.cfg.Icons)
	case "temp":
		return 5
	case "feels":
		return 6
	case "conditions":
		return 16
	case "mm", "rain", "wind", "gusts", "humidity", "dew", "uv", "cloud", "visibility":
		return 5
	case "dir":
		return 3
	case "pressure":
		return 6
	}
	return 6
}

func (x ctx) leftAligned(name string) bool {
	if _, ok := x.custom(name); ok {
		return false // custom columns are numeric
	}
	switch name {
	case "hour", "icon", "temp", "feels", "conditions":
		return true
	}
	return false
}

// visible drops columns that have nothing to say: the icon column when icons
// are off, and the rain pair on a dry window.
func (x ctx) visible() []string {
	var out []string
	for _, name := range x.cfg.Columns {
		if name == "icon" && x.cfg.Icons == "none" {
			continue
		}
		if (name == "mm" || name == "rain") && !x.wet {
			continue
		}
		out = append(out, name)
	}
	return out
}

// row assembles one line from cells, padding each to its column width BEFORE
// colouring it. Escape sequences carry no display width, so padding a coloured
// string misaligns every column to its right -- invisible when piped, obvious
// in a terminal.
func (x ctx) row(cells map[string]cell) string {
	var b strings.Builder
	for _, name := range x.visible() {
		c := cells[name]
		w := x.colWidth(name)
		padded := PadLeft(c.text, w)
		if x.leftAligned(name) {
			padded = Pad(c.text, w)
		}
		b.WriteString(" ")
		b.WriteString(x.c(c.style, padded))
	}
	return strings.TrimRight(b.String(), " ")
}

func (x ctx) table(v View) []string {
	out := []string{""}

	headers := map[string]cell{}
	for _, name := range x.visible() {
		text := x.cat.Header(name)
		if cc, ok := x.custom(name); ok {
			// A user-declared label is not ours to translate.
			text = customLabel(name, cc)
		}
		headers[name] = cell{text: text, style: ""}
	}
	out = append(out, x.c(Underline, x.rowPlain(headers)))

	day := v.Rows[0].When.Format("2006-01-02")
	prevCode := -1
	for i, r := range v.Rows {
		if d := r.When.Format("2006-01-02"); d != day {
			day = d
			sep := " -- " + x.cat.Date(r.When) + " --"
			if sun, ok := v.Sun[d]; ok {
				sep += fmt.Sprintf("  %s %s / %s", x.cat.Word("sun"), sun[0], sun[1])
			}
			out = append(out, x.c(Dim, sep))
			prevCode = -1 // repeat the conditions once per day for context
		}
		out = append(out, x.row(x.cells(r, i == 0, &prevCode)))
	}
	return out
}

// rowPlain is the header row: padded like the data but never coloured per cell,
// so the underline runs unbroken across it.
func (x ctx) rowPlain(cells map[string]cell) string {
	var b strings.Builder
	for _, name := range x.visible() {
		w := x.colWidth(name)
		text := cells[name].text
		padded := PadLeft(text, w)
		if x.leftAligned(name) {
			padded = Pad(text, w)
		}
		b.WriteString(" ")
		b.WriteString(padded)
	}
	return b.String()
}

func (x ctx) cells(r openmeteo.Row, isNow bool, prevCode *int) map[string]cell {
	out := map[string]cell{}
	temp, hasTemp := r.Val("temperature_2m")

	for _, name := range x.visible() {
		if cc, ok := x.custom(name); ok {
			out[name] = x.customCell(r, name, cc)
			continue
		}
		switch name {
		case "hour":
			style := Reset
			if isNow {
				style = Bold
			}
			out[name] = cell{text: r.When.Format("15"), style: style}

		case "icon":
			out[name] = cell{text: Icon(x.cfg.Icons, r.Code)}

		case "temp":
			style := TempStyle(x.celsius(temp))
			// The current hour keeps its emphasis on top of the heat colour.
			if isNow {
				style = Bold + ";" + style
			}
			out[name] = cell{text: fmt.Sprintf("%d°", Deg(temp)), style: style}

		case "feels":
			text := ""
			if feels, ok := r.Val("apparent_temperature"); ok && hasTemp {
				// Only shown when it differs; otherwise it is a column of noise.
				if abs(feels-temp) >= 1 {
					text = fmt.Sprintf("(%d)", Deg(feels))
				}
			}
			out[name] = cell{text: text, style: Dim}

		case "conditions":
			text := ""
			// Only when they change: an unbroken column of "overcast" hides the
			// hour it stops being overcast, which is the only interesting part.
			if r.Code != *prevCode {
				text = Truncate(x.cat.Condition(r.Code), x.colWidth(name))
			}
			out[name] = cell{text: text}

		case "mm":
			mm, _ := r.Val("precipitation")
			style := Dim
			if mm > 0 {
				style = Cyan
			}
			out[name] = cell{text: round1(mm), style: style}

		case "rain":
			p, _ := r.Val("precipitation_probability")
			style := Dim
			if p >= 50 {
				style = Yellow
			}
			out[name] = cell{text: fmt.Sprintf("%d%%", int(p)), style: style}

		case "wind":
			v, _ := r.Val("wind_speed_10m")
			out[name] = cell{text: fmt.Sprintf("%d", int(v))}

		case "gusts":
			v, _ := r.Val("wind_gusts_10m")
			style := ""
			if v >= 60 {
				style = Yellow
			}
			out[name] = cell{text: fmt.Sprintf("%d", int(v)), style: style}

		case "dir":
			v, _ := r.Val("wind_direction_10m")
			out[name] = cell{text: compass(v)}

		case "humidity":
			v, _ := r.Val("relative_humidity_2m")
			out[name] = cell{text: fmt.Sprintf("%d%%", int(v)), style: Dim}

		case "dew":
			v, _ := r.Val("dew_point_2m")
			out[name] = cell{text: fmt.Sprintf("%d°", Deg(v)), style: Dim}

		case "uv":
			v, _ := r.Val("uv_index")
			style := Dim
			if v >= 6 {
				style = Yellow
			}
			out[name] = cell{text: round1(v), style: style}

		case "cloud":
			v, _ := r.Val("cloud_cover")
			out[name] = cell{text: fmt.Sprintf("%d%%", int(v)), style: Dim}

		case "pressure":
			v, _ := r.Val("pressure_msl")
			out[name] = cell{text: fmt.Sprintf("%d", int(v)), style: Dim}

		case "visibility":
			v, _ := r.Val("visibility")
			out[name] = cell{text: fmt.Sprintf("%.0fkm", v/1000), style: Dim}
		}
	}
	*prevCode = r.Code
	return out
}

func abs(f float64) float64 {
	if f < 0 {
		return -f
	}
	return f
}

// CustomKey is where a custom column's value lives in a Row.
//
// Prefixed so a column called "temp" or "visibility" can never shadow the API
// field of the same name that a built-in column reads.
func CustomKey(name string) string { return "x:" + name }

// customCell formats one user-declared column.
//
// A value the API did not supply renders blank rather than as zero: for an
// allergen or a soil reading, "no data" and "none" are different claims.
func (x ctx) customCell(r openmeteo.Row, name string, cc config.CustomColumn) cell {
	key := cc.Field
	if cc.Source == "air" {
		key = CustomKey(name)
	}
	v, ok := r.Val(key)
	if !ok {
		return cell{text: "", style: Dim}
	}
	return cell{
		text:  fmt.Sprintf("%.*f%s", cc.Decimals, v, cc.Suffix),
		style: Dim,
	}
}