acorde-core 1.1.1

use super::gm::instrument_range;
use super::score::Score;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

/// A structural error found by [`validate`].
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ValidationError {
    /// The score has no parts to validate.
    EmptyScore,
    /// A part has no staves.
    PartWithoutStaves { part: usize },
    /// A staff has no measures.
    StaffWithoutMeasures { part: usize, staff: usize },
    /// Staves in one part do not cover the same number of measures.
    MeasureCountMismatch {
        part: usize,
        staff: usize,
        expected: usize,
        found: usize,
    },
    /// A time signature has an unsupported numerator or denominator.
    InvalidTimeSignature {
        part: usize,
        staff: usize,
        measure: usize,
        numerator: u8,
        denominator: u8,
    },
    /// Beat-count mismatch: the notes in a voice don't fill the time signature.
    BeatCount {
        part: usize,
        staff: usize,
        measure: usize,
        voice: usize,
        expected_beats: f64,
        found_beats: f64,
    },
    /// A note pitch lies outside the practical range for the part's GM instrument.
    OutOfRange {
        part_index: usize,
        staff_index: usize,
        measure_index: usize,
        note_index: usize,
        pitch_midi: u8,
        instrument_range: (u8, u8),
    },
    /// Tablature staff metadata is internally inconsistent.
    InvalidTablature {
        part: usize,
        staff: usize,
        reason: TablatureValidationReason,
    },
    /// A note's explicit string is not present on its tablature staff.
    TabPositionOutOfRange {
        part: usize,
        staff: usize,
        measure: usize,
        voice: usize,
        note: usize,
        string: u8,
        lines: u8,
    },
    /// A pitch's microtonal cents component is outside the canonical -99..99 range.
    MicrotoneOutOfRange {
        part: usize,
        staff: usize,
        measure: usize,
        voice: usize,
        note: usize,
        pitch: usize,
        microtone_cents: i16,
    },
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum TablatureValidationReason {
    InvalidLineCount { lines: u8 },
    TooManyTunings { tuning_count: usize, lines: u8 },
    TuningOutOfMidiRange { index: usize, midi: i16 },
}

/// A non-fatal advisory warning found by [`validate`].
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ValidationWarning {
    /// A measure's beat count is less than the time signature (incomplete bar).
    IncompleteBar {
        part: usize,
        staff: usize,
        measure: usize,
        expected_beats: f64,
        actual_beats: f64,
    },
    /// Two volta brackets in the same staff overlap or share the same number.
    OverlappingVolta { part: usize, staff: usize },
    /// A part has no notes across all measures.
    EmptyPart { part: usize },
    /// The same rehearsal mark text appears more than once.
    DuplicateRehearsalMark { mark: String },
}

/// Combined result of [`validate`]: errors that indicate broken structure, plus advisory warnings.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ValidationReport {
    pub errors: Vec<ValidationError>,
    pub warnings: Vec<ValidationWarning>,
}

impl ValidationReport {
    /// `true` when there are no errors (warnings may still be present).
    pub fn is_valid(&self) -> bool {
        self.errors.is_empty()
    }
}

/// Check every voice in every measure for structural correctness.
///
/// Checks performed:
/// - **Errors**: beat-count mismatch, out-of-range pitch.
/// - **Warnings**: incomplete bar (underfull voice), overlapping volta brackets,
///   empty parts, duplicate rehearsal marks.
///
/// Multi-rest placeholder measures and empty voices are skipped.
/// Percussion parts (MIDI channel 9) are exempt from pitch-range checks.
pub fn validate(score: &Score) -> ValidationReport {
    let mut errors = Vec::new();
    let mut warnings = Vec::new();

    let mut rehearsal_counts: HashMap<String, usize> = HashMap::new();

    if score.parts.is_empty() {
        errors.push(ValidationError::EmptyScore);
    }

    for (pi, part) in score.parts.iter().enumerate() {
        let range = instrument_range(part.midi_program);
        let is_percussion = part.midi_channel == 9;
        let mut part_has_notes = false;

        if part.staves.is_empty() {
            errors.push(ValidationError::PartWithoutStaves { part: pi });
            continue;
        }

        let expected_measure_count = part.staves[0].measures.len();

        for (si, staff) in part.staves.iter().enumerate() {
            if staff.measures.is_empty() {
                errors.push(ValidationError::StaffWithoutMeasures {
                    part: pi,
                    staff: si,
                });
                continue;
            }
            if staff.measures.len() != expected_measure_count {
                errors.push(ValidationError::MeasureCountMismatch {
                    part: pi,
                    staff: si,
                    expected: expected_measure_count,
                    found: staff.measures.len(),
                });
            }

            if let Some(tab) = &staff.tablature {
                if !(1..=64).contains(&tab.lines) {
                    errors.push(ValidationError::InvalidTablature {
                        part: pi,
                        staff: si,
                        reason: TablatureValidationReason::InvalidLineCount { lines: tab.lines },
                    });
                } else if tab.tuning_midi.len() > usize::from(tab.lines) {
                    errors.push(ValidationError::InvalidTablature {
                        part: pi,
                        staff: si,
                        reason: TablatureValidationReason::TooManyTunings {
                            tuning_count: tab.tuning_midi.len(),
                            lines: tab.lines,
                        },
                    });
                }
                for (index, &midi) in tab.tuning_midi.iter().enumerate() {
                    if !(0..=127).contains(&midi) {
                        errors.push(ValidationError::InvalidTablature {
                            part: pi,
                            staff: si,
                            reason: TablatureValidationReason::TuningOutOfMidiRange { index, midi },
                        });
                    }
                }
            }

            let mut current_ts = score.settings.time_signature.clone();
            let mut volta_numbers_seen: Vec<u8> = Vec::new();

            for (mi, measure) in staff.measures.iter().enumerate() {
                if let Some(ts) = &measure.time_sig {
                    current_ts = ts.clone();
                }
                if !valid_time_signature(&current_ts) {
                    errors.push(ValidationError::InvalidTimeSignature {
                        part: pi,
                        staff: si,
                        measure: mi,
                        numerator: current_ts.numerator,
                        denominator: current_ts.denominator,
                    });
                    continue;
                }
                if measure.multi_rest_count.is_some() {
                    continue;
                }

                // Rehearsal mark deduplication
                if let Some(ref mark) = measure.rehearsal {
                    let entry = rehearsal_counts.entry(mark.clone()).or_insert(0);
                    *entry += 1;
                }

                // Volta overlap detection
                if let Some(ref volta) = measure.volta {
                    if volta_numbers_seen.contains(&volta.number) {
                        warnings.push(ValidationWarning::OverlappingVolta {
                            part: pi,
                            staff: si,
                        });
                    } else {
                        volta_numbers_seen.push(volta.number);
                    }
                }

                let expected = current_ts.total_beats();
                for (vi, voice) in measure.voices.iter().enumerate() {
                    if voice.is_empty() {
                        continue;
                    }
                    let non_rest_count: usize = voice.iter().filter(|n| !n.is_rest).count();
                    if non_rest_count > 0 {
                        part_has_notes = true;
                    }
                    let total: f64 = voice.iter().map(|n| n.beats()).sum();
                    if total > expected + 0.02 {
                        errors.push(ValidationError::BeatCount {
                            part: pi,
                            staff: si,
                            measure: mi,
                            voice: vi,
                            expected_beats: expected,
                            found_beats: total,
                        });
                    } else if total < expected - 0.02 && non_rest_count > 0 {
                        warnings.push(ValidationWarning::IncompleteBar {
                            part: pi,
                            staff: si,
                            measure: mi,
                            expected_beats: expected,
                            actual_beats: total,
                        });
                    }

                    for (ni, note) in voice.iter().enumerate() {
                        if note.is_rest || note.is_grace {
                            continue;
                        }
                        for (pitch_index, pitch) in note.pitches.iter().enumerate() {
                            if !(-99..=99).contains(&pitch.microtone_cents) {
                                errors.push(ValidationError::MicrotoneOutOfRange {
                                    part: pi,
                                    staff: si,
                                    measure: mi,
                                    voice: vi,
                                    note: ni,
                                    pitch: pitch_index,
                                    microtone_cents: pitch.microtone_cents,
                                });
                            }
                        }
                    }

                    if !is_percussion {
                        let transpose = staff.transpose_semitones;
                        for (ni, note) in voice.iter().enumerate() {
                            if note.is_rest || note.is_grace {
                                continue;
                            }
                            if let Some(tab) = &staff.tablature {
                                let positions =
                                    note.tab_position.iter().chain(note.tab_positions.iter());
                                for position in positions {
                                    if position.string == 0 || position.string > tab.lines {
                                        errors.push(ValidationError::TabPositionOutOfRange {
                                            part: pi,
                                            staff: si,
                                            measure: mi,
                                            voice: vi,
                                            note: ni,
                                            string: position.string,
                                            lines: tab.lines,
                                        });
                                    }
                                }
                            }
                            for pitch in &note.pitches {
                                let midi = (pitch.to_midi() + transpose as i16).clamp(0, 127) as u8;
                                if midi < range.0 || midi > range.1 {
                                    errors.push(ValidationError::OutOfRange {
                                        part_index: pi,
                                        staff_index: si,
                                        measure_index: mi,
                                        note_index: ni,
                                        pitch_midi: midi,
                                        instrument_range: range,
                                    });
                                }
                            }
                        }
                    }
                }
            }
        }

        if !part_has_notes {
            warnings.push(ValidationWarning::EmptyPart { part: pi });
        }
    }

    for (mark, count) in &rehearsal_counts {
        if *count > 1 {
            warnings.push(ValidationWarning::DuplicateRehearsalMark { mark: mark.clone() });
        }
    }

    ValidationReport { errors, warnings }
}

fn valid_time_signature(time: &super::notation::TimeSignature) -> bool {
    time.numerator > 0 && matches!(time.denominator, 1 | 2 | 4 | 8 | 16 | 32 | 64)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::model::{
        duration::Duration,
        pitch::{Pitch, Step},
        score::{Note, Score},
    };

    #[test]
    fn validate_clean_score_returns_empty_errors() {
        let score = Score::new("T", 120, 4, 4, 0, 1);
        assert!(validate(&score).errors.is_empty());
    }

    #[test]
    fn validate_empty_score_returns_structural_error() {
        let mut score = Score::new("T", 120, 4, 4, 0, 1);
        score.parts.clear();
        let report = validate(&score);
        assert!(
            report
                .errors
                .iter()
                .any(|error| matches!(error, ValidationError::EmptyScore))
        );
    }

    #[test]
    fn validate_detects_missing_staves_and_measures() {
        let mut score = Score::new("T", 120, 4, 4, 0, 1);
        score.parts[0].staves.clear();
        let report = validate(&score);
        assert!(
            report
                .errors
                .iter()
                .any(|error| matches!(error, ValidationError::PartWithoutStaves { part: 0 }))
        );

        score.parts[0].staves.push(crate::model::score::Staff::new(
            crate::model::notation::Clef::Treble,
        ));
        let report = validate(&score);
        assert!(report.errors.iter().any(|error| matches!(
            error,
            ValidationError::StaffWithoutMeasures { part: 0, staff: 0 }
        )));
    }

    #[test]
    fn validate_detects_staff_measure_count_mismatch() {
        let mut score = Score::template(crate::model::score::ScoreTemplate::Piano);
        score.parts[0].staves[1].measures.pop();
        let report = validate(&score);
        assert!(report.errors.iter().any(|error| matches!(
            error,
            ValidationError::MeasureCountMismatch {
                part: 0,
                staff: 1,
                expected: 4,
                found: 3
            }
        )));
    }

    #[test]
    fn validate_detects_invalid_time_signature() {
        let mut score = Score::new("T", 120, 4, 4, 0, 1);
        score.parts[0].staves[0].measures[0].time_sig =
            Some(crate::model::notation::TimeSignature {
                numerator: 0,
                denominator: 3,
            });
        let report = validate(&score);
        assert!(report.errors.iter().any(|error| matches!(
            error,
            ValidationError::InvalidTimeSignature {
                part: 0,
                staff: 0,
                measure: 0,
                numerator: 0,
                denominator: 3
            }
        )));
    }

    #[test]
    fn validate_overfull_measure_returns_error() {
        let mut score = Score::new("T", 120, 4, 4, 0, 1);
        score.parts[0].staves[0].measures[0].voices[0]
            .push(Note::new(Pitch::new(Step::C, 4), Duration::Quarter));
        let report = validate(&score);
        assert!(!report.errors.is_empty());
        assert!(matches!(
            report.errors[0],
            ValidationError::BeatCount {
                measure: 0,
                voice: 0,
                ..
            }
        ));
    }

    #[test]
    fn validate_skips_multi_rest() {
        let mut score = Score::new("T", 120, 4, 4, 0, 1);
        score.parts[0].staves[0].measures[0].multi_rest_count = Some(4);
        score.parts[0].staves[0].measures[0].voices[0].clear();
        assert!(validate(&score).errors.is_empty());
    }

    #[test]
    fn validate_out_of_range_pitch_detected() {
        // Piano (program 0): range 21–108. C9 (midi=120) is out of range.
        let mut score = Score::new("T", 120, 4, 4, 0, 1);
        score.parts[0].midi_program = 0;
        score.parts[0].staves[0].measures[0].voices[0] =
            vec![Note::new(Pitch::new(Step::C, 9), Duration::Whole)];
        let report = validate(&score);
        assert!(report.errors.iter().any(
            |e| matches!(e, ValidationError::OutOfRange { pitch_midi, .. } if *pitch_midi == 120)
        ));
    }

    #[test]
    fn validate_percussion_channel_skips_range_check() {
        // Channel 9 = percussion; even extreme pitches should not trigger OutOfRange.
        let mut score = Score::new("T", 120, 4, 4, 0, 1);
        score.parts[0].midi_channel = 9;
        score.parts[0].midi_program = 0;
        score.parts[0].staves[0].measures[0].voices[0] =
            vec![Note::new(Pitch::new(Step::C, 9), Duration::Whole)];
        let report = validate(&score);
        assert!(
            !report
                .errors
                .iter()
                .any(|e| matches!(e, ValidationError::OutOfRange { .. }))
        );
    }

    #[test]
    fn validate_in_range_pitch_ok() {
        // Piano C4 (midi=60) is in range 21–108.
        let mut score = Score::new("T", 120, 4, 4, 0, 1);
        score.parts[0].midi_program = 0;
        score.parts[0].staves[0].measures[0].voices[0] =
            vec![Note::new(Pitch::new(Step::C, 4), Duration::Whole)];
        assert!(
            !validate(&score)
                .errors
                .iter()
                .any(|e| matches!(e, ValidationError::OutOfRange { .. }))
        );
    }

    #[test]
    fn validate_rejects_deserialized_microtone_out_of_range() {
        let mut score = Score::new("T", 120, 4, 4, 0, 1);
        let mut note = Note::new(Pitch::new(Step::C, 4), Duration::Whole);
        note.pitches[0].microtone_cents = 100;
        score.parts[0].staves[0].measures[0].voices[0] = vec![note];
        let report = validate(&score);
        assert!(report.errors.iter().any(|error| matches!(
            error,
            ValidationError::MicrotoneOutOfRange {
                microtone_cents: 100,
                ..
            }
        )));
    }

    #[test]
    fn validate_rejects_invalid_tablature_metadata_and_positions() {
        let mut score = Score::new("Tab", 120, 4, 4, 0, 1);
        score.parts[0].staves[0].tablature = Some(super::super::notation::TablatureConfig {
            lines: 6,
            tuning_midi: vec![64, 59, 55, 50, 45, 40, 35],
            capo: 0,
        });
        let mut note = Note::new(Pitch::new(Step::E, 4), Duration::Whole);
        note.tab_position = Some(super::super::notation::TabPosition { string: 7, fret: 0 });
        note.tab_positions = vec![super::super::notation::TabPosition { string: 8, fret: 3 }];
        score.parts[0].staves[0].measures[0].voices[0] = vec![note];

        let report = validate(&score);
        assert!(report.errors.iter().any(|error| matches!(
            error,
            ValidationError::InvalidTablature {
                reason: TablatureValidationReason::TooManyTunings { .. },
                ..
            }
        )));
        assert!(
            report
                .errors
                .iter()
                .any(|error| matches!(error, ValidationError::TabPositionOutOfRange { .. }))
        );
        assert_eq!(
            report
                .errors
                .iter()
                .filter(|error| matches!(error, ValidationError::TabPositionOutOfRange { .. }))
                .count(),
            2
        );
    }

    #[test]
    fn validate_empty_part_warning() {
        let score = Score::new("T", 120, 4, 4, 0, 1);
        let report = validate(&score);
        assert!(
            report
                .warnings
                .iter()
                .any(|w| matches!(w, ValidationWarning::EmptyPart { part: 0 }))
        );
    }

    #[test]
    fn validate_duplicate_rehearsal_mark_warning() {
        use crate::model::score::Score;
        let mut score = Score::new("T", 120, 4, 4, 0, 2);
        score.parts[0].staves[0].measures[0].rehearsal = Some("A".to_string());
        score.parts[0].staves[0].measures[1].rehearsal = Some("A".to_string());
        let report = validate(&score);
        assert!(report.warnings.iter().any(
            |w| matches!(w, ValidationWarning::DuplicateRehearsalMark { mark } if mark == "A")
        ));
    }
}