package tui

import (
	"fmt"
	"strings"

	"github.com/charmbracelet/lipgloss"

	"proxyctl/internal/app"
	"proxyctl/internal/profile"
)

// helpDialogState is an overlay, not a page. Keeping only its viewport state
// here means opening Help cannot replace the page, selection, focus, or the
// viewport beneath it.
type helpDialogState struct {
	open              bool
	offset            int
	confirmationAbove bool
}

func (h *helpDialogState) show() {
	h.open = true
	h.offset = 0
	// An explicitly opened Help dialog is newer than any visible confirmation.
	h.confirmationAbove = false
}

func (h *helpDialogState) close() { *h = helpDialogState{} }

func (h helpDialogState) top(confirmation *app.Confirmation) bool {
	return h.open && (confirmation == nil || !h.confirmationAbove)
}

func (h *helpDialogState) update(key string) {
	switch key {
	case "up", "k":
		h.offset = max(0, h.offset-1)
	case "down", "j":
		h.offset++
	case "pgup":
		h.offset = max(0, h.offset-5)
	case "pgdown":
		h.offset += 5
	case "home":
		h.offset = 0
	case "end":
		h.offset = 1 << 20 // the viewport clamps this to the final content line
	case "q", "esc":
		h.close()
	}
}

func (m Model) dashboardQuitAvailable() bool {
	return m.page == mainPage && !m.help.open && !m.picker.open &&
		m.driftResolutionTargetID == "" && m.operation.confirmation == nil
}

func (p terminalPresentation) helpDialogView(model presentationState) terminalPage {
	content := lipgloss.NewStyle().Width(max(1, model.terminal.width)).Render(protectRenderedText(p.contextualHelp(model)))
	exitHint := "Ctrl+C: exit"
	if model.operation.active {
		exitHint = "Ctrl+C: defer safe exit"
	}
	if model.operation.exitDeferred {
		exitHint = "Exit pending until safe completion"
	}
	return terminalPage{
		primary:       content,
		footer:        "↑/k ↓/j PgUp/PgDn Home/End: scroll\nq/Esc: close Help  " + exitHint,
		focusLine:     -1,
		primaryOffset: model.help.dialog.offset,
	}
}

func (p terminalPresentation) contextualHelp(model presentationState) string {
	dashboard, operation := model.dashboard, model.operation
	profiles, form := model.profile, model.form.state
	var body strings.Builder
	body.WriteString(p.theme.section.Render("Contextual Help"))
	body.WriteString("\nThis describes the page or dialog beneath Help. While Help is open, only its scrolling and closing keys plus global Ctrl+C are accepted; the underlying state remains unchanged.\n\n")

	switch {
	case operation.confirmation != nil:
		body.WriteString(p.theme.section.Render("Safety confirmation"))
		fmt.Fprintf(&body, "\n%s\n", operation.confirmation.Title)
		if operation.confirmation.Summary != "" {
			fmt.Fprintf(&body, "%s\n", operation.confirmation.Summary)
		}
		body.WriteString("Left/Right, Tab, or Shift+Tab changes the focused choice. Enter chooses it. y confirms. n, q, or Escape cancels. ")
		if operation.confirmationDialog != nil {
			body.WriteByte('\n')
			body.WriteString(confirmationFocusDescription(*operation.confirmationDialog))
		}
		body.WriteByte('\n')
	case profiles.deletion != nil:
		body.WriteString(p.theme.section.Render("Delete confirmation"))
		fmt.Fprintf(&body, "\nDelete Proxy Profile %q. Deletion cannot be undone.\n", profiles.deletion.name)
		body.WriteString("Left/Right, Tab, or Shift+Tab changes the focused choice. Enter chooses it. y deletes. n, q, or Escape cancels. ")
		body.WriteByte('\n')
		body.WriteString(confirmationFocusDescription(profiles.deletion.dialog))
		body.WriteByte('\n')
	case dashboard.picker.open:
		body.WriteString(p.theme.section.Render("Active Profile picker"))
		body.WriteString("\nType to filter Proxy Profiles; q is ordinary search input here. Up/Down or Ctrl+P/Ctrl+N selects, and PgUp/PgDn moves by a page. Enter activates the selection. Escape cancels.\n")
	case dashboard.driftResolutionTargetID != "":
		body.WriteString(p.theme.section.Render("Drift Resolution dialog"))
		body.WriteString("\nr reapplies the Active Profile. o restores original configuration when ownership evidence permits. Enter, q, or Escape cancels.\n")
		if selected, ok := newTargetCatalog(model.snapshot, true, dashboard.driftResolutionTargetID).selected(dashboard.driftResolutionTargetID); ok {
			for _, kind := range []app.TargetActionKind{app.ReapplyActiveProfileAction, app.RestoreOriginalAction} {
				action, found := driftResolutionAction(selected, kind)
				if found && action.Available {
					fmt.Fprintf(&body, "%s: available.\n", targetActionLabel(kind))
				} else {
					reason := action.DisabledReason
					if reason == "" {
						reason = "unavailable"
					}
					fmt.Fprintf(&body, "%s: disabled — %s.\n", targetActionLabel(kind), reason)
				}
			}
		}
	case model.page == profilesPage:
		body.WriteString(p.theme.section.Render("Profile management"))
		if selected, ok := profileAt(model.snapshot, profiles.selected); ok {
			fmt.Fprintf(&body, "\nSelected Profile: %s.\n", selected.Name)
			body.WriteString("Up/Down or j/k selects a Profile. PgUp/PgDn scrolls its details. n creates, e or Enter edits, and d opens the delete confirmation. q or Escape returns to the dashboard.\n")
			if operation.active || operation.exitDeferred {
				body.WriteString("Profile modifications are disabled until the current mutation completes.\n")
			} else {
				body.WriteString("Create, Edit selected Profile, and Delete selected Profile are available.\n")
			}
		} else {
			body.WriteString("\nNo Proxy Profiles are saved. n creates one. q or Escape returns to the dashboard.\n")
		}
	case model.page == formPage:
		body.WriteString(p.theme.section.Render("Profile form"))
		if form.field >= 0 && form.field < len(form.inputs) {
			fmt.Fprintf(&body, "\nFocus: %s field.\n", form.inputs[form.field].label)
		}
		body.WriteString("Type or paste to insert at the cursor. Left/Right moves the cursor; Home/End moves to the field boundary; Backspace/Delete removes text. Long inputs scroll horizontally. Tab or Down moves to the next field; Shift+Tab or Up moves to the previous field. Ctrl+T changes mode while preserving Profile values. Ctrl+S validates and saves. q or Escape cancels and returns to Profile management.\n")
		if form.currentField() == profile.BypassField {
			body.WriteString("PgUp/PgDn scrolls the normalized Bypass preview while the Bypass field is focused.\n")
		}
		if form.profile.Mode == profile.SingleMode {
			switch {
			case form.probe.active:
				body.WriteString("Protocol Probe is in progress for the Single proxy URL field. Its progress remains attached to that field; Ctrl+D does not start a duplicate probe while that field is focused.\n")
			case form.currentField() == profile.SingleURLField:
				body.WriteString("Ctrl+D explicitly runs Protocol Probe for the focused Single proxy URL field. It never runs on form entry, focus changes, or save.\n")
			default:
				body.WriteString("The Single proxy URL field visibly offers Protocol Probe; focus that field and press Ctrl+D to run it explicitly.\n")
			}
		} else if form.hasProbeSourceAttachment() {
			body.WriteString("The Protocol Probe result remains attached to its read-only initiating Single proxy URL context. The HTTP, HTTPS, and ALL/SOCKS values were generated from that probe.\n")
		}
	default:
		body.WriteString(p.theme.section.Render("Dashboard"))
		focus := "Targets focus"
		if dashboard.focus == targetDetailsPane {
			focus = "Target details focus"
		}
		fmt.Fprintf(&body, "\nContext: %s.\n", focus)
		catalog := newTargetCatalog(model.snapshot, dashboard.showUnavailable, dashboard.selectedTargetID)
		if selected, ok := catalog.selected(dashboard.selectedTargetID); ok {
			fmt.Fprintf(&body, "Selected Target: %s. State: %s.\n", selected.Description.Name, targetStateLabel(selected.State))
			availability := targetMutationAvailability(selected, true, operation.active || operation.exitDeferred)
			label := targetActionLabel(selected.PrimaryAction.Kind)
			if availability.available {
				fmt.Fprintf(&body, "Primary action: %s — available with Space.\n", label)
			} else {
				fmt.Fprintf(&body, "Primary action: %s — disabled: %s.\n", label, availability.reason)
			}
		}
		if dashboard.focus == targetDetailsPane {
			body.WriteString("Up/Down, j/k, and PgUp/PgDn scroll Target details. Tab focuses Targets.\n")
		} else {
			body.WriteString("Up/Down or j/k selects a Target. Tab focuses Target details.\n")
		}
		if operation.active || operation.exitDeferred {
			body.WriteString("u still shows or hides unavailable Targets. p, m, r, and Space modifications are disabled until the current mutation completes.\n")
		} else {
			body.WriteString("u shows or hides unavailable Targets. p opens the Active Profile picker. m opens Profile management. r refreshes Targets.\n")
		}
	}

	body.WriteString("\n")
	body.WriteString(p.theme.section.Render("Operation state"))
	switch {
	case operation.exitDeferred:
		body.WriteString("\nExit is pending. Read-only browsing and Help remain available; all new work is disabled until the mutation completes safely.\n")
	case operation.active:
		body.WriteString("\nMutation in progress. Target selection, details scrolling, and Help remain available.\nConflicting mutations are disabled until completion. Ctrl+C requests a deferred safe exit.\n")
	default:
		body.WriteString("\nNo mutation is in progress. Ctrl+C exits immediately.\n")
	}
	if operation.currentError != nil && model.page == mainPage && operation.confirmation == nil && !dashboard.picker.open && dashboard.driftResolutionTargetID == "" {
		body.WriteString("e expands or collapses the current error; x acknowledges it.\n")
	}

	if model.page == mainPage && profiles.deletion == nil {
		body.WriteString("\n")
		body.WriteString(p.theme.section.Render("Built-in Target reference"))
		body.WriteString("\n")
		for _, item := range model.snapshot.Targets {
			fmt.Fprintf(&body, "%s\n%s\n%s\n", item.Description.Name, item.Description.Summary, item.Description.Details)
			if item.Available {
				fmt.Fprintf(&body, "Detected: %s\n\n", item.AvailabilityEvidence)
			} else {
				fmt.Fprintf(&body, "Not detected: %s\n\n", item.AvailabilityEvidence)
			}
		}
	}

	body.WriteString("\n")
	body.WriteString(p.theme.section.Render("Dialog and page navigation"))
	body.WriteString("\nEscape closes the top dialog. With no dialog open, Escape returns one page level. q closes Help and confirmations, returns from child pages, and exits only from the unobscured dashboard. Picker search accepts q as text.\n")
	body.WriteString("Inputs are delivered only to the top dialog; they cannot activate content behind it. A newly requested safety confirmation appears above older Help.\n")

	body.WriteString("\n")
	body.WriteString(p.theme.section.Render("Global exit safety"))
	body.WriteString("\nCtrl+C requests exit from every page and dialog. During a system mutation, proxyctl waits for safe completion and rejects new work before exiting.\n")
	return body.String()
}

func confirmationFocusDescription(dialog confirmationDialog) string {
	label := dialog.request.CancelLabel
	if label == "" {
		label = "Cancel"
	}
	if dialog.confirmFocused {
		label = dialog.request.ConfirmLabel
		if label == "" {
			label = "Confirm"
		}
	}
	return label + " is focused."
}