package tui

import (
    "os"
    "strings"

    "charm.land/lipgloss/v2"
)

// noColor detects NO_COLOR environment variable.
var noColor = os.Getenv("NO_COLOR") != ""

// Nord Color Palette (https://www.nordtheme.com/)
// Nord Dark (Polar Night + Frost)
var (
    // Polar Night (dark theme background/text)
    nord0 = "#2E3440" // base background
    nord1 = "#3B4252" // lighter background
    nord2 = "#434C5E" // selection/background elements
    nord3 = "#4C566A" // comments/borders

    // Frost (dark theme foreground/text)
    nord4 = "#D8DEE9" // primary text
    nord5 = "#E5E9F0" // secondary text
    nord6 = "#ECEFF4" // emphasized text

    // Aurora (dark theme accents)
    nord7  = "#BF616A" // red (errors/warnings)
    nord8  = "#D08770" // orange (warnings)
    nord9  = "#EBCB8B" // yellow (warnings/highlights)
    nord10 = "#A3BE8C" // green (success)
    nord11 = "#B48EAD" // purple (special)
    nord12 = "#88C0D0" // cyan (primary accent)
    nord13 = "#81A1C1" // blue (secondary accent)
    nord14 = "#5E81AC" // dark blue (links/details)
)

// Nord Light (Aurora variant for light theme)
var (
    // Light background
    nordLight0 = "#FFFFFF" // base background
    nordLight1 = "#ECEFF4" // lighter background
    nordLight2 = "#E5E9F0" // selection
    nordLight3 = "#D8DEE9" // borders

    // Light text
    nordLight4 = "#4C566A" // primary text
    nordLight5 = "#3B4252" // secondary text
    nordLight6 = "#2E3440" // emphasized text

    // Aurora accents (same as dark, work well on light)
    nordLight7  = "#BF616A" // red
    nordLight8  = "#D08770" // orange
    nordLight9  = "#EBCB8B" // yellow
    nordLight10 = "#A3BE8C" // green
    nordLight11 = "#B48EAD" // purple
    nordLight12 = "#88C0D0" // cyan
    nordLight13 = "#81A1C1" // blue
    nordLight14 = "#5E81AC" // dark blue
)

// Styles holds all pre-built lipgloss styles.
type Styles struct {
    // Header
    HeaderTitle lipgloss.Style
    HeaderInfo  lipgloss.Style
    HeaderRule  lipgloss.Style

    // Messages
    UserLabel    lipgloss.Style
    UserContent  lipgloss.Style
    AsstLabel    lipgloss.Style
    AsstContent  lipgloss.Style
    RoleRule     lipgloss.Style
    StreamCursor lipgloss.Style

    // Tools
    ToolCallIcon    lipgloss.Style
    ToolCallText    lipgloss.Style
    ToolResultIcon  lipgloss.Style
    ToolResultText  lipgloss.Style
    ToolErrorIcon   lipgloss.Style
    ToolErrorText   lipgloss.Style
    ToolDoneIcon    lipgloss.Style
    ToolDoneText    lipgloss.Style
    ToolRunningText lipgloss.Style
    ToolDetailText  lipgloss.Style

    // Footer
    Divider        lipgloss.Style
    StatusDot      lipgloss.Style
    StatusText     lipgloss.Style
    StatusCheck    lipgloss.Style
    StatusError    lipgloss.Style
    ApprovalPrompt lipgloss.Style
    StreamHint     lipgloss.Style
    ErrorText      lipgloss.Style
    Dimmed         lipgloss.Style

    // System messages
    SystemText  lipgloss.Style
    WelcomeHint lipgloss.Style

    // Completion popup
    CompletionBorder   lipgloss.Style
    CompletionSelected lipgloss.Style

    // Completion modal
    CompletionFilter    lipgloss.Style
    CompletionCursor    lipgloss.Style
    CompletionCategory  lipgloss.Style
    CompletionFooter    lipgloss.Style
    CompletionSearching lipgloss.Style

    // Startup progress
    StartupCheck  lipgloss.Style
    StartupFail   lipgloss.Style
    StartupLabel  lipgloss.Style
    StartupDetail lipgloss.Style
    StartupSpin   lipgloss.Style

    // Mode badges
    ModeAsk   lipgloss.Style
    ModePlan  lipgloss.Style
    ModeBuild lipgloss.Style

    // Context percentage fuel gauge
    ContextPctLow  lipgloss.Style
    ContextPctMid  lipgloss.Style
    ContextPctHigh lipgloss.Style

    // Tool type rendering
    ToolBashCmd lipgloss.Style

    // Diff view
    DiffAdded   lipgloss.Style
    DiffRemoved lipgloss.Style
    DiffContext lipgloss.Style
    DiffHeader  lipgloss.Style

    // Thinking display
    ThinkingHeader  lipgloss.Style
    ThinkingContent lipgloss.Style
    ThinkingBorder  lipgloss.Style

    // Shared overlay styles (used by help, model picker, sessions, plan form, completion)
    OverlayTitle  lipgloss.Style
    OverlayBorder string
    OverlayAccent lipgloss.Style
    OverlayDim    lipgloss.Style

    // Focus indicators
    FocusIndicator lipgloss.Style
}

// NewStyles creates a Styles set based on the background color.
func NewStyles(isDark bool) Styles {
    if noColor {
        return plainStyles()
    }
    return adaptiveStyles(isDark)
}

func adaptiveStyles(isDark bool) Styles {
    // Select Nord palette based on theme
    var (
        colorDim     string
        colorMuted   string
        colorText    string
        colorAccent  string
        colorAccent2 string
        colorError   string
        colorSuccess string
        colorSpecial string
        colorBorder  string
    )

    if isDark {
        // Nord Dark Theme (Polar Night + Frost + Aurora)
        colorDim = nord3      // #4C566A - comments/borders
        colorMuted = nord4    // #D8DEE9 - primary text (muted)
        colorText = nord5     // #E5E9F0 - secondary text
        colorAccent = nord12  // #88C0D0 - cyan (primary accent)
        colorAccent2 = nord13 // #81A1C1 - blue (secondary accent)
        colorError = nord7    // #BF616A - red
        colorSuccess = nord10 // #A3BE8C - green
        colorSpecial = nord11 // #B48EAD - purple
        colorBorder = nord3
    } else {
        // Nord Light Theme (Aurora)
        colorDim = nordLight3      // #D8DEE9 - borders
        colorMuted = nordLight4    // #4C566A - primary text (muted)
        colorText = nordLight5     // #3B4252 - secondary text
        colorAccent = nordLight12  // #88C0D0 - cyan
        colorAccent2 = nordLight13 // #81A1C1 - blue
        colorError = nordLight7    // #BF616A - red
        colorSuccess = nordLight10 // #A3BE8C - green
        colorSpecial = nordLight11 // #B48EAD - purple
        colorBorder = nordLight3
    }

    // Helper for theme-specific colors
    nordColor := func(dark, light string) string {
        if isDark {
            return dark
        }
        return light
    }

    return Styles{
        HeaderTitle: lipgloss.NewStyle().
            Bold(true).
            Foreground(lipgloss.Color(colorAccent)).
            PaddingLeft(1),
        HeaderInfo: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)).
            PaddingRight(1),
        HeaderRule: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),

        UserLabel: lipgloss.NewStyle().
            Bold(true).
            Foreground(lipgloss.Color(colorAccent2)).
            PaddingLeft(2),
        UserContent: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorText)).
            PaddingLeft(2),
        AsstLabel: lipgloss.NewStyle().
            Bold(true).
            Foreground(lipgloss.Color(colorSuccess)).
            PaddingLeft(2),
        AsstContent: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorText)).
            PaddingLeft(4),
        RoleRule: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),
        StreamCursor: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent)).
            Bold(true),

        ToolCallIcon: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorSpecial)).
            PaddingLeft(4),
        ToolCallText: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorSpecial)),
        ToolResultIcon: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)).
            PaddingLeft(4),
        ToolResultText: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),
        ToolErrorIcon: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorError)).
            PaddingLeft(4),
        ToolErrorText: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorError)),
        ToolDoneIcon: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorSuccess)).
            PaddingLeft(4),
        ToolDoneText: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),
        ToolRunningText: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent)),
        ToolDetailText: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorMuted)),

        Divider: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),
        StatusDot: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent)).
            PaddingLeft(1),
        StatusText: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),
        StatusCheck: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorSuccess)).
            PaddingLeft(1),
        StatusError: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorError)).
            PaddingLeft(1),
        ApprovalPrompt: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent)).
            Bold(true),
        StreamHint: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)).
            Italic(true),
        ErrorText: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorError)).
            Bold(true).
            PaddingLeft(2),
        Dimmed: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),

        SystemText: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorText)).
            Italic(true).
            PaddingLeft(2),
        WelcomeHint: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent2)).
            Bold(true),

        CompletionBorder: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),
        CompletionSelected: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent)).
            Bold(true),

        CompletionFilter: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorText)),
        CompletionCursor: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent)).
            Bold(true),
        CompletionCategory: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),
        CompletionFooter: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)).
            Italic(true),
        CompletionSearching: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorSpecial)).
            Italic(true),

        StartupCheck: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorSuccess)),
        StartupFail: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorError)),
        StartupLabel: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorText)),
        StartupDetail: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),
        StartupSpin: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent)),

        ModeAsk: lipgloss.NewStyle().
            Bold(true).
            Foreground(lipgloss.Color(colorAccent2)),
        ModePlan: lipgloss.NewStyle().
            Bold(true).
            Foreground(lipgloss.Color(nordColor(nord9, nordLight9))), // yellow
        ModeBuild: lipgloss.NewStyle().
            Bold(true).
            Foreground(lipgloss.Color(colorSuccess)),

        ContextPctLow: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorSuccess)),
        ContextPctMid: lipgloss.NewStyle().
            Foreground(lipgloss.Color(nordColor(nord9, nordLight9))),
        ContextPctHigh: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorError)),

        ToolBashCmd: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)).
            Italic(true),

        DiffAdded: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorSuccess)).
            PaddingLeft(6),
        DiffRemoved: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorError)).
            PaddingLeft(6),
        DiffContext: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)).
            PaddingLeft(6),
        DiffHeader: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent)).
            PaddingLeft(6),

        ThinkingHeader: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorSpecial)).
            Italic(true),
        ThinkingContent: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)).
            PaddingLeft(4),
        ThinkingBorder: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),

        OverlayTitle: lipgloss.NewStyle().
            Bold(true).
            Foreground(lipgloss.Color(colorAccent)),
        OverlayBorder: colorBorder,
        OverlayAccent: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent2)).
            Bold(true),
        OverlayDim: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorDim)),

        FocusIndicator: lipgloss.NewStyle().
            Foreground(lipgloss.Color(colorAccent)).
            Bold(true),
    }
}

func plainStyles() Styles {
    p := lipgloss.NewStyle()
    b := lipgloss.NewStyle().Bold(true)
    pl2 := lipgloss.NewStyle().PaddingLeft(2)
    pl4 := lipgloss.NewStyle().PaddingLeft(4)
    return Styles{
        HeaderTitle: b.PaddingLeft(1),
        HeaderInfo:  p.PaddingRight(1),
        HeaderRule:  p,

        UserLabel:    b.PaddingLeft(2),
        UserContent:  pl2,
        AsstLabel:    b.PaddingLeft(2),
        AsstContent:  pl2,
        RoleRule:     p,
        StreamCursor: b,

        ToolCallIcon:    pl4,
        ToolCallText:    p,
        ToolResultIcon:  pl4,
        ToolResultText:  p,
        ToolErrorIcon:   pl4,
        ToolErrorText:   b,
        ToolDoneIcon:    pl4,
        ToolDoneText:    p,
        ToolRunningText: p,
        ToolDetailText:  p,

        Divider:        p,
        StatusDot:      p.PaddingLeft(1),
        StatusText:     p,
        StatusCheck:    p.PaddingLeft(1),
        StatusError:    p.PaddingLeft(1),
        ApprovalPrompt: b,
        StreamHint:     p.Italic(true),
        ErrorText:  b.PaddingLeft(2),
        Dimmed:     p,

        SystemText:  p.PaddingLeft(2).Italic(true),
        WelcomeHint: b,

        CompletionBorder:   p,
        CompletionSelected: b,

        CompletionFilter:    p,
        CompletionCursor:    b,
        CompletionCategory:  p,
        CompletionFooter:    p.Italic(true),
        CompletionSearching: p.Italic(true),

        StartupCheck:  p,
        StartupFail:   b,
        StartupLabel:  p,
        StartupDetail: p,
        StartupSpin:   p,

        ModeAsk:   b,
        ModePlan:  b,
        ModeBuild: b,

        ContextPctLow:  p,
        ContextPctMid:  p,
        ContextPctHigh: p,

        ToolBashCmd: p.Italic(true),

        DiffAdded:   pl4,
        DiffRemoved: pl4,
        DiffContext: pl4,
        DiffHeader:  pl4,

        ThinkingHeader:  p.Italic(true),
        ThinkingContent: pl4,
        ThinkingBorder:  p,

        OverlayTitle:  b,
        OverlayBorder: "",
        OverlayAccent: b,
        OverlayDim:    p,

        FocusIndicator: b,
    }
}

// rule generates a horizontal line of the given width using a thin character.
func rule(width int) string {
    if width < 1 {
        return ""
    }
    return strings.Repeat("─", width)
}

// thickRule generates a horizontal line using a thick character.
func thickRule(width int) string {
    if width < 1 {
        return ""
    }
    return strings.Repeat("━", width)
}