//! Import-wizard key handling: which key means what depends on the step, and that
//! decision is pure, so it lives here (improvise-2wm, gotcha 22).

use crate::command::key::KeyCode;
use crate::import::wizard::{ImportWizard, WizardStep};
use crate::ui::effect::{self, Effect, WizardOp};

use super::core::{Cmd, CmdContext};

/// Dispatch the current key to the import wizard.
#[derive(Debug)]
pub struct HandleWizardKey;
impl Cmd for HandleWizardKey {
    fn name(&self) -> &'static str {
        "handle-wizard-key"
    }
    fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
        ctx.wizard
            .map(|wizard| step_effects(wizard, ctx.key_code))
            .unwrap_or_default()
    }
}

fn step_effects(wizard: &ImportWizard, key: KeyCode) -> Vec<Box<dyn Effect>> {
    match wizard.step {
        WizardStep::Preview => preview_keys(key),
        WizardStep::SelectArrayPath => select_path_keys(key),
        WizardStep::ReviewProposals => review_proposal_keys(key),
        WizardStep::ConfigureDates => configure_date_keys(key),
        WizardStep::ResolveDuplicates => resolve_duplicate_keys(key),
        WizardStep::NameDuplicateCategory => name_duplicate_category_keys(key),
        WizardStep::DefineFormulas if wizard.formula_editing => formula_edit_keys(key),
        WizardStep::DefineFormulas => formula_list_keys(key),
        WizardStep::NameModel => name_model_keys(key),
        WizardStep::Done => done_keys(key),
    }
}

// ── Per-step key tables ──────────────────────────────────────────────────────

fn preview_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Enter | KeyCode::Char(' ') => op(WizardOp::Advance),
        KeyCode::Esc => close(),
        _ => back_key(key),
    }
}

fn select_path_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Enter => op(WizardOp::ConfirmPath),
        _ => cursor_keys(key),
    }
}

fn review_proposal_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Char(' ') => op(WizardOp::ToggleProposal),
        KeyCode::Char('c') => op(WizardOp::CycleProposalKind),
        KeyCode::Enter => op(WizardOp::Advance),
        _ => cursor_keys(key),
    }
}

fn configure_date_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Char(' ') => op(WizardOp::ToggleDateComponent),
        KeyCode::Char('s') => op(WizardOp::ToggleDateShape),
        KeyCode::Enter => op(WizardOp::Advance),
        _ => cursor_keys(key),
    }
}

/// Up/Down choose an option; PageUp/PageDown scroll the colliding records.
fn resolve_duplicate_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Enter => op(WizardOp::ChooseDuplicate),
        _ => scroll_keys(key).unwrap_or_else(|| cursor_keys(key)),
    }
}

fn name_duplicate_category_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Enter => op(WizardOp::Advance),
        KeyCode::Backspace => op(WizardOp::PopDuplicateNameChar),
        KeyCode::Char(c) => op(WizardOp::PushDuplicateNameChar(c)),
        KeyCode::Esc => close(),
        _ => back_key(key),
    }
}

fn formula_list_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Char('n') => op(WizardOp::StartFormulaEdit),
        KeyCode::Char('d') => op(WizardOp::DeleteFormula),
        KeyCode::Enter => op(WizardOp::Advance),
        _ => cursor_keys(key),
    }
}

fn formula_edit_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Enter => op(WizardOp::ConfirmFormula),
        KeyCode::Esc => op(WizardOp::CancelFormulaEdit),
        KeyCode::Backspace => op(WizardOp::PopFormulaChar),
        KeyCode::Char(c) => op(WizardOp::PushFormulaChar(c)),
        _ => ignored(),
    }
}

fn name_model_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Enter => op(WizardOp::Build),
        KeyCode::Backspace => op(WizardOp::PopNameChar),
        KeyCode::Char(c) => op(WizardOp::PushNameChar(c)),
        KeyCode::Esc => close(),
        _ => back_key(key),
    }
}

/// The confirmation step: Enter installs the built workbook, and both Esc and Left
/// return to `NameModel` — Esc here does not discard the import (improvise-907).
fn done_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Enter => vec![Box::new(effect::AcceptWizardModel)],
        KeyCode::Esc => op(WizardOp::Back),
        KeyCode::Down | KeyCode::Char('j') => op(WizardOp::Scroll(1)),
        KeyCode::Up | KeyCode::Char('k') => op(WizardOp::Scroll(-1)),
        _ => scroll_keys(key).unwrap_or_else(|| back_key(key)),
    }
}

/// PageUp/PageDown move a step's scrolling list by one item.
fn scroll_keys(key: KeyCode) -> Option<Vec<Box<dyn Effect>>> {
    match key {
        KeyCode::PageDown => Some(op(WizardOp::Scroll(1))),
        KeyCode::PageUp => Some(op(WizardOp::Scroll(-1))),
        _ => None,
    }
}

/// The list-navigation keys every browsing step shares.
fn cursor_keys(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Up | KeyCode::Char('k') => op(WizardOp::MoveCursor(-1)),
        KeyCode::Down | KeyCode::Char('j') => op(WizardOp::MoveCursor(1)),
        KeyCode::Esc => close(),
        _ => back_key(key),
    }
}

/// Left steps back on every step. It is the one key free everywhere: Backspace edits
/// buffers and `h` is a printable the name step needs (improvise-907).
fn back_key(key: KeyCode) -> Vec<Box<dyn Effect>> {
    match key {
        KeyCode::Left => op(WizardOp::Back),
        _ => ignored(),
    }
}

// ── Effect constructors ──────────────────────────────────────────────────────

fn op(op: WizardOp) -> Vec<Box<dyn Effect>> {
    vec![Box::new(effect::WizardApply(op))]
}

fn close() -> Vec<Box<dyn Effect>> {
    vec![Box::new(effect::CloseWizard)]
}

fn ignored() -> Vec<Box<dyn Effect>> {
    vec![]
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::import::wizard::ImportWizard;

    fn wizard_at(step: WizardStep) -> ImportWizard {
        let mut w = ImportWizard::new(serde_json::json!([
            {"region": "East", "revenue": 1.0},
            {"region": "West", "revenue": 2.0},
        ]));
        w.step = step;
        w
    }

    fn ops(wizard: &ImportWizard, key: KeyCode) -> String {
        format!("{:?}", step_effects(wizard, key))
    }

    /// Every browsing step shares j/k/arrow navigation and Esc-to-close, so
    /// the shared `cursor_keys` fallback must reach all of them.
    #[test]
    fn browsing_steps_share_cursor_and_close_keys() {
        for step in [
            WizardStep::SelectArrayPath,
            WizardStep::ReviewProposals,
            WizardStep::ConfigureDates,
            WizardStep::DefineFormulas,
        ] {
            let w = wizard_at(step.clone());
            assert!(
                ops(&w, KeyCode::Char('j')).contains("MoveCursor(1)"),
                "{step:?} should move down on j"
            );
            assert!(
                ops(&w, KeyCode::Up).contains("MoveCursor(-1)"),
                "{step:?} should move up on Up"
            );
            assert!(
                ops(&w, KeyCode::Esc).contains("CloseWizard"),
                "{step:?} should close on Esc"
            );
        }
    }

    /// While typing a formula, Esc backs out of the edit only — it must not
    /// close the wizard — and printable keys go into the formula buffer.
    #[test]
    fn formula_editing_shadows_the_browsing_keys() {
        let mut w = wizard_at(WizardStep::DefineFormulas);
        w.formula_editing = true;
        assert!(ops(&w, KeyCode::Esc).contains("CancelFormulaEdit"));
        assert!(ops(&w, KeyCode::Char('j')).contains("PushFormulaChar('j')"));
        assert!(ops(&w, KeyCode::Enter).contains("ConfirmFormula"));
    }

    /// Enter on the name step builds the workbook rather than advancing the step
    /// machine; every other printable key edits the name.
    #[test]
    fn name_model_enter_builds_the_model() {
        let w = wizard_at(WizardStep::NameModel);
        assert!(ops(&w, KeyCode::Enter).contains("Build"));
        assert!(ops(&w, KeyCode::Char('j')).contains("PushNameChar('j')"));
        assert!(ops(&w, KeyCode::Backspace).contains("PopNameChar"));
    }

    /// Left steps back on every step, including the two text-entry ones —
    /// there must be no step from which the only exit is Esc (improvise-907).
    #[test]
    fn every_step_binds_left_as_back() {
        for step in [
            WizardStep::Preview,
            WizardStep::SelectArrayPath,
            WizardStep::ReviewProposals,
            WizardStep::ConfigureDates,
            WizardStep::ResolveDuplicates,
            WizardStep::NameDuplicateCategory,
            WizardStep::DefineFormulas,
            WizardStep::NameModel,
            WizardStep::Done,
        ] {
            let w = wizard_at(step.clone());
            assert!(
                ops(&w, KeyCode::Left).contains("Back"),
                "{step:?} should step back on Left"
            );
        }
    }

    /// On the confirmation step Enter installs the built workbook and Esc steps back;
    /// no key closes the wizard outright (improvise-907, from improvise-c6j).
    #[test]
    fn done_confirms_on_enter_and_steps_back_on_esc() {
        let w = wizard_at(WizardStep::Done);
        assert!(ops(&w, KeyCode::Enter).contains("AcceptWizardModel"));
        assert!(ops(&w, KeyCode::Esc).contains("Back"));
        assert_eq!(step_effects(&w, KeyCode::Char('z')).len(), 0);
    }

    /// improvise-cgqt: Enter takes the option under the cursor, never a bare
    /// advance, which would skip the question; the page keys scroll the list.
    #[test]
    fn the_duplicates_step_chooses_on_enter_and_scrolls_on_the_page_keys() {
        let w = wizard_at(WizardStep::ResolveDuplicates);
        assert_eq!(ops(&w, KeyCode::Enter), "[WizardApply(ChooseDuplicate)]");
        assert!(ops(&w, KeyCode::Down).contains("MoveCursor(1)"));
        assert!(ops(&w, KeyCode::PageDown).contains("Scroll(1)"));
        assert!(ops(&w, KeyCode::PageUp).contains("Scroll(-1)"));
        assert!(ops(&w, KeyCode::Esc).contains("CloseWizard"));
    }

    /// The name step is text entry: `j` is a letter here, not a cursor key.
    #[test]
    fn the_category_name_step_types_into_the_name() {
        let w = wizard_at(WizardStep::NameDuplicateCategory);
        assert!(ops(&w, KeyCode::Char('j')).contains("PushDuplicateNameChar('j')"));
        assert!(ops(&w, KeyCode::Backspace).contains("PopDuplicateNameChar"));
        assert!(ops(&w, KeyCode::Enter).contains("Advance"));
    }

    /// The confirm step's warnings scroll, so a long list is never cut off.
    #[test]
    fn done_scrolls_its_warnings() {
        let w = wizard_at(WizardStep::Done);
        assert!(ops(&w, KeyCode::Down).contains("Scroll(1)"));
        assert!(ops(&w, KeyCode::PageUp).contains("Scroll(-1)"));
    }

    #[test]
    fn unbound_keys_emit_nothing() {
        let w = wizard_at(WizardStep::ReviewProposals);
        assert_eq!(step_effects(&w, KeyCode::Char('Z')).len(), 0);
    }
}